Imatges de pàgina
PDF
EPUB

NEW✨

[blocks in formation]

750. Colour. F. VERSMANN, Bury Court, St. Mary Axe, London. Dated March 25, 1861. Not proceeded with. THIS specification relates to the economical employment of the compounds of titanium as pigments or colouring agents.

It is to be regretted that the sources of colouring matter here referred have not yet been practically utilised. The sources of titanium are by no means rare, titanic acid is found tolerably pure in the mineral rutile, and titaniferous iron is actually abundant. The chemical reactions of titanium give rise to a fair proportion of coloured products, -among others there is the pale blue oxide, somewhat similar to the corresponding tungsten compound, this appears, however, to be of an alterable nature. If titanic acid be heated in a porcelain tube through which a current of dry ammonia gas is passed, it is converted into a violet powder of a permanent character, having the composition TiN. Other nitrides of titanium have been prepared by the action of the same gas upon the bichloride, when brilliant purple scales are formed, which in turn yield a lustrous yellow product by afterwards passing hydrogen through the tube.

As long since as the year 1846, Elsner proposed the substitution of "titanium green" for the poisonous arsenical pigment commonly used in the manufacture of paper hangings; we are not aware that this material-the ferrocyanide of titanium-has ever met with any extensive application, but it may be of interest to repeat here M. Elsner's original directions for its preparation :-Washed rutile, or iserine, is decomposed with twelve parts by weight of bisulphate of potassa in a Hessian crucible; the fused mass is pulverised, digested at 50 degrees Centigrade with hydrochloric acid previously diluted with twice its weight of water, and filtered. The filtrate is evaporated until a drop solidifies upon a cold plate; at this stage it forms, in the evaporating dish, a paste which is well drained upon a filter, and then continuously boiled in a porcelain basin with solution of sal-ammoniac in order to prevent the formation of a basic iron salt. This process and subsequent washing and filtering renders the difficultly soluble titanic acid almost white, and for the purpose of preparing the ferrocyanide of titanium the pasty mass obtained in the above manner is digested, at about 50 or 60 degrees, with dilute hydrochloric acid until, if possible, complete solution ensues, and the acid liquid after the addition of ferrocyanide of potassium rapidly heated to ebullition. The beautiful green precipitate is washed with water acidulated with hydrochloric acid, and dried with great care, since it decomposes at temperatures above 100 degrees. The colour, however, is certainly inferior to the arsenical green.

777. Shear Steel, R. A. BROOMAN, Fleet Street, London, A communication. Dated March 28, 1861. For the purpose of preventing the access of atmospheric air, and the gases from the fire, operating injuriously on the puddled steel during the heating process to which it is subjected as a preliminary to welding, it is directed to enclose the piles of raw steel in a covered crucible or other conveniently-shaped receptacle, such as a clay retort or muffle, luted at all the joints, with exception of a small aperture left open to enable the temperature of its heated contents, being determined by inspection. The welding heat approaching so nearly that of the melting point of steel, necessitates constant watching, so that the metal may be withdrawn from the furnace at the proper moment, and hammered or passed between the rollers. Such an arrangement offers facilities for long-continued heating of the steel before rolling, by which its working qualities are said to be much improved, the deteriorating action of oxygen being at the same time excluded.

Grants of Provisional Protection for Six Months. 2694. William Smith, Leek, Staffordshire, "Improvements in the preservation of stone, brick, and other such materials used in building, applicable also to the waterproofing of walls."-Petition recorded October 26, 1861. 2710. Richard Gibbon, Royal Brewery, Brentford, Middlesex, Improvements in machinery or apparatus for preparing grain for brewers."

[ocr errors]

2810. Aristide Balthazard Berard, Avenue Montaigne, Paris, "Improvements in apparatus for separating metals from their ores."-Petitions recorded November 8, 1861.

2845. Michael Henry, Fleet Street, London, “An im provement in, and composition for, treating iron and steel, and articles manufactured thereof."-A communication from Alphonse Muller de la Mothe, Boulevart St. Martin, Paris.-Petitions recorded November 12, 1861.

2846. Thomas Littleton Holt, Brook House, Brentford, Middlesex, "A new method of making paper from the cochleria armoracia, or horse radish."'

2863. George Tomlinson Bousfield, Loughborough Park, Brixton, Surrey, "Improvements in the manufacture of soap."-A communication from Campbell Morfit, New York, U.S.

2871. Frederick Robert Hughes, Borrowstouness, and Thomas Richardson, Newcastle-upon-Tyne, "Improvements in treating certain natural saline compounds to fit them for agricultural use, and in order to obtain potash and other salts."-Petitions recorded November 14, 1861.

2879. Louis Anthony Soupart, Brussels, Belgium, "Improvements in the mode of preparing and subsequently tanning hides or skins."-Petitions recorded November 15, 1861.

2903. Theophilus Redwood, Montague Street, Russell Square, London, "Improvements in the manufacture of starch and of a vegetable sizing powder."

2911. George Gwilliam, Savoy, Strand, London, "Improvements in the manufacture or production of plate glass."

2920. John Henry Johnson, Lincoln's Inn Fields, London, "Improvements in the treatment of zinc ores, and in the apparatus employed therein, which improvements are also applicable to the manufacture of phosphorus."-A communication from Adrien Muller, Paris.-Petitions recorded November 20, 1861,

2922. James Parkinson and Charles Henry Minchen, Manchester, "Improvement in the Davy' or other safety lamps for miners."

2926. John Stubbs, Winsford, Cheshire, "Improvements in apparatus for heating and evaporating brine in the manufacture of salt."

2930. William Hirst, Halifax, Yorkshire, "Improvements in the manufacture of paste, which is also applicable to sizing purposes."

14

Miscellaneous-Answers to Correspondents.

CHEMICAL NEWS, Jan. 4, 1862.

2952. Jean Baptiste Hulard and Louis Guillaume progress of invention, seem to complete the charm which Poupel, Paris, "An improved process for hardening stones and plaster of Paris, and making them impervious

[blocks in formation]

2988. Horatio Mearing, Great Randolph Street, Camden Town, London, "An improved lucifer match, and prepared paper for igniting the same."

2994. Michael Henry, Fleet Street, London, "Improve ments in the manufacture of soap, and the preparation of materials for the purpose."-A communication from Louis Marie Théophile Riot, Boulevart St. Martin, Paris.

2127. Frederick Tolhausen, Boulevart Bonne-Nouvelle, Paris, "A new and economical method of producing dynamic electricity, thereby obtaining useful chemical compounds."-A communication from Jean Baptiste Théodore Rousse, Imperial Lyceum, St. Etienne, France. -Petition recorded August 26, 1861.

2351. John Oliver, Colchester, Essex, John Granthan, Nicholas Lane, London, William Sinnock, Sylvan Cottage, Woodford, Essex, and Montague Richard Leverson, St. Helen's Place, London, "Improvements in the mode of obtaining certain chemical substances, and in the treatment of vegetable fibre, and in obtaining manurial and other products therefrom."-Petition recorded September 20, 1861.

Notices to Proceed.

1893. Wentworth Lascelles Scott, Bayswater, London, "Improvements in preparing red, purple, and certain other dyes."-Petitions recorded July 29, 1861.

2810. Aristide Balthazard Berard, Avenue Mentaigne, Paris, "Improvements in apparatus for separating metals from their ores."-Petition recorded November 8, 1861. 2831. George Fergusson Wilson and George Payne, Sherwood Works, Battersea, Surrey, "Improvements in treating fatty and oily matters."-Petitions recorded December 11, 1861.

2863. George Tomlinson Bousfield, Loughborough Park, Brixton, Surrey, "Improvements in the manufacture of soap."-A communication from Campbell Morfit, New York, U.S.-Petition recorded December 13, 1861.

MISCELLANEOUS.

ROYAL INSTITUTION OF GREAT BRITAIN. We have great pleasure in announcing to our readers that, having received Professor Tyndall's special permission to report his Course of Six Lectures "On Light' (adapted to a juvenile auditory), now in course of delivery at the Royal Institution, the First Lecture will appear, fully illustrated, in our next Number.

The following are the subjects of the course :

always attaches to a visit to the Polytechnic. Among the novelties which have been introduced, foremost should be mentioned the magnificent series of dissolving views illustrating American scenery. The Falls of Niagara and surrounding country in its wintry aspect, its caverns and awful precipices clothed with icicles so stupendous in magnitude that were it not for the actual photograph being thrown upon the screen, doubts might be entertained as to the faithfulness of the representation. The instantaneous view taken in the Broadway, New York, is a good illustration of American life and commercialactivity, so also is the railway-station, in which is seen the extraordinary locomotive engine, so different in figure from those used in our own country, on account of wood being there chiefly employed as fuel. The entire series, indeed, reflect great credit upon the energetic exertions of Mr. Eagland, who crossed the Atlantic with the special object of securing these interesting photographic representations of American life and scenery. The optical facilities of the Institution are likewise employed in the illustration of Mr. Pepper's Lecture on the Science of the Armstrong, Whitworth, and other rifled guns; in the description of England's dockyards and iron-clad ships of war; and, with the assistance of Mr. Childe's phantasmagoria apparatus, for the performance of an optical version of Grimaldi's pantomime, of which the clever shadow effects, introduced so successentitled, Mother Goose and the Golden Egg, in the course fully at the Crystal Palace, are exhibited on the large Some of the recent results of experimental science Lecture on the " are very ably and popularly treated by Mr. Pepper, in his Magnificent Field of Discovery Opened hoff."" out by the Researches of Professors Bunsen and KirchWith the aid of a Duboscq's lamp, in which the the electric arc between carbon points, the differently various metallic compounds are submitted to the heat of coloured spectral bands are beautifully exhibited upon flame to light of its own colour was that experiment a large white disc. The opacity of the yellow sodium alone which was less conclusively exhibited in this manner, apparently from its requiring extreme delicacy of manipulation. We never remember to have seen so many interesting novelties within the same compass of time and space as that which composes the Christmas entertainment at the Polytechnic Institution.

screen.

Royal Institution.—On Tuesday, January 7, at three o'clock, Professor Tyndall will deliver a lecture "On Light" (Juvenile Lectures).

ANSWERS TO CORRESPONDENTS.

All Editorial Communications are to be addressed to the EDITOR; and Advertisements and Business Communications to the PUBLISHER at

The Propagation of Light-The Reflection of Light the Office, 1, Wine Office Court, Fleet Street, London, E.C. from Plane Surfaces-The Reflection of Light from Curved Surfaces.

The Refraction of Light-Prisms and Lenses.
The Solar Microscope-The Eye.

Combined Action of Refraction and Reflection-Mirage.
-Colours: Analysis and Synthesis of White Light.
The Solar Spectrum-The Spectra of Incandescent
Metallic Vapours.

Elementary Facts of Interference-Elementary Facts of Polarization.

Polytechnic Institution.—The Christmas programme of this old and deservedly popular scientific Institution includes several new features of interest. The tastefully arranged decorations in the hall and galleries, disposed just now in accordance with the custom of the season, and the gigantic Christmas tree, present a pleasing appearance of winter gaiety, while the exhibition of works of art, the machinery in motion, models and other illustrations of the

*** In publishing letters from our Correspondents we do not thereby adopt the views of the writers. Our intention to give both sides of a question will frequently oblige us to publish opinions with which we do not agree.

Vol. IV. of the CHEMICAL NEWS, containing a copious Index, is now ready, price 128., by post, 128. 8d., handsomely bound in cloth, goldlettered. The cases for binding may be obtained at our Office, price 18. 6d. Subscribers may have their copies bound for 28. if sent to our Office, or, if accompanied by a cloth case, for 6d. A few copies of Vols. I. II. and III. can still be had. Vol. V. commenced on January 4, 1862, and will be complete in 26 numbers.

O. R., Ph.D.-Answered in our last Number.

C. R. The oxide of iron, not being a conductor of electricity, will not be decomposed.

tion spoken of. J Horsley-Received. We shall be glad to receive the communica

ERRATA-"Analysis of Yeast," page 338, for Scheikundize Onderhoskinzer read Scheikundige Onderzoekingen.

THE CHEMICAL NEWS.

VOL. V. No. 110.-January 11, 1862.

SCIENTIFIC AND ANALYTICAL CHEMISTRY.

Researches on the Relations existing between Atomic Weights, by M. J. S. STAS, Member of the Royal Academy of Belgium.

(Continued from page 2.)

Analysis of Sulphate of Silver.-I endeavoured to perform the synthesis of sulphate of silver, but was obliged to renounce this project on account of the mechanical carrying off of the silver when I effected the solution of the metal in a platinum vessel, and of the impossibility of finishing the desiccation of the sulphate in a platinum vessel when I effected the solution of the silver in a Bohemian glass flask, as I did in the case of sulphate of lead. I was, therefore, obliged to be satisfied by performing its analysis, which would only determine the amount of silver contained therein. I determined this by reducing the sulphate with hydrogen, as has been already done by M. Struve.

I employed in these experiments three specimens of sulphate of silver. One I obtained by pouring into dilute and boiling sulphuric acid, contained in a platinum vessel, a solution of pure nitrate of silver. The liquid being cooled, the mother-liquor was removed and replaced three separate times by water acidulated with weak sulphuric acid, and the whole brought each time to ebullition and kept at this temperature for half-an-hour. The sulphate of silver deposited, upon cooling, was then washed in cold water until the washing-water came away quite neutral. Before using it in the experiment, I dried it at nearly 350° in a current of dry air, freed from all organic matter by passing through a glass tube filled with oxide of copper heated to redness. With this object I heated it in a Liebig's desiccator, placed in a bath of chloride of zinc.

To procure the second specimen of the salt, I attacked directly in a platinum dish, concentrated and pure sulphuric acid by means of silver prepared with sugar of milk, and in which I had found it impossible to discover any traces of foreign matter. When all the silver was transformed into sulphate I drove off, by heat, as much as possible of the acid in excess.

After cooling the vessel, I washed the salt in water, so as to remove the last trace of sulphuric acid which had escaped the action of heat. Then I heated it in the some platinum vessel much beyond the boiling-point of sulphuric acid. I then introduced it, quite warm, into a flask with a ground stopper previously heated and dried. Before using it in the analysis, I heated it again in the same tube to beyond the boiling-point of sulphuric acid.

Sulphate of silver is of great stability. Although it requires almost a dull red heat to fuse it, it can be liquified without sensible loss of weight, provided the operation takes place away from organic dust in the air and in a platinum vessel; for a glass vessel is attacked by fused sulphate of silver.

250 grammes of sulphate of silver obtained by this latter method were dissolved by ebullition in the water employed to wash the salt, acidulated with sulphuric acid. After the liquid is slowly cooled, the salt separates from it in the form of voluminous prisms, colourless and limpid as water. One of these prisms weighed 11.8 grammes. These prisms, when heated to 300°, decrepitate rather violently. They can then be heated to above the boiling point of sulphuric acid, and can even be fused, without causing the sulphate sensibly to lose weight.

Sulphate of silver prepared by the action of sulphuric acid on nitrate of silver, and by the action of this metal on concentrated sulphuric acid, appears in the form of a has been heated to 350°, provided that during its desiccrystalline powder, of dazzling whiteness, even when it cation a current of air perfectly deprived of organic matter has been made use of. Without this precaution, it assumes in the desiccating apparatus at first a green and then a violet tint. In this case, when dissolved in

water, it leaves a blackish residue, which becomes silverwhite at a red heat. Its pulverulent state obliged me to weigh it in vacuo.

This is the arrangement which I adopted to estimate the silver by means of the action of hydrogen :-I took a Bohemian glass tube, eighteen millimètres in diameter, and seventy-five centimètres long, drawn at one end. After having dried it at a high temperature, I introduced it into a large tube for weighing in vacuo, and made a another large tube similar to the first in its exterior vacuum in the apparatus, which was equipoised with volume and the nature of its surface. At the same time, I placed the necessary weights to bring it into equilibrium in the opposite pan of the balance.

of dried sulphate of silver, taking care to leave that I then filled the Bohemian glass tube two-thirds full third of the tube empty which was near to the drawnout point. After having again heated the sulphate of silver enclosed in the tube in a current of pure, dry air, I immediately introduced it into the vacuum apparatus and removed all the air. When perfectly cool I weighed it.

Finally, I placed the tube containing sulphate of silver in communication with a large apparatus for the disengagement of pure dry hydrogen. To obtain this gas, I took all the precautions recommended by M. Dumas in his Memoir on the Synthesis of Water, only that I used fused caustic potash as the desiccating agent, wishing thus to avoid the presence of traces of sulphurous acid in the hydrogen.

This tube rested in an iron box entirely filled with magnesia, and very slightly inclined to the drawn-out end, which led into a large empty receiver. When the

[blocks in formation]

apparatus was quite full of hydrogen, I heated to the boiling-point of sulphuric acid that part of the box corresponding to the empty portion of the tube. I then gently raised the temperature of that portion of the tube which contained the sulphate of silver. When I saw the reduction of the salt commence, I endeavoured as much as possible to keep the temperature uniform, so as to avoid attacking the glass and volatilising the silver. The decomposition of the sulphate of silver takes place with extreme nicety and regularity; it is a true substitution of hydrogen for silver. Indeed, if the temperature is kept sufficiently low, there is only silver and sulphuric acid produced, which latter runs down, owing to the inclination of the tube; scarcely any traces of sulphurous acid being smelt. In proportion as the sulphate of silver is reduced, the quantity of sulphuric acid produced becomes sufficient to arrive at that part of the tube which is heated to the boiling point of this acid. It is there reduced by the excess of hydrogen disengaged into sulphurous acid and water or into sulphur and water. Sulphuric acid is the only product which I have seen formed when the action of the hydrogen on the sulphate of silver has taken place at a low temperature. As the temperature is more raised, water and sulphide of silver are at first produced, and then metallic silver and hydro-sulphuric acid. In all the determinations of the results which are given below, I have endeavoured as much as possible to avoid the formation of sulphide of silver and the subsequent production of hydro-sulphuric acid. Nevertheless, I have always noticed the presence of hydro-sulphuric acid at the conclusion of all the reductions, when the tube was heated to very dull redness in the current of hydrogen. I have, indeed, only stopped the current when paper impregnated with a salt of lead, placed in front of the hydrogen disengagement tube, did not show the slightest trace of sulphuretted hydrogen. In all these determinations the residue of silver was in a spongy form, and of a dead white appearance. In order to be quite certain of the absence of all traces of sulphide of silver in the metal, I caused to pass through the tube, heated to dull redness, a current of air, in order to burn the sulphur. In only one experiment did I smell a sulphurous odour. When the operation was terminated, the commencement of the empty portion of the tube in which the reduction of the sulphuric acid into sulphurous acid and water took place was covered with a mirror of silver arising from the silver carried by the sulphuric acid in the state of sulphate. But there always remained at least twelve or fifteen centimètres of the tube which did not show the slightest trace of metallic deposit. The acid water condensed in the large receiver, which was in communication with the tube, contained traces of silver, but too

small to be estimated.

The silver having been weighed, I always dissolved the metal in dilute nitric acid, to see if any sulphide of silver were present. In no experiment did I find any. To render the control complete, I perfectly washed and dried the tube in which the reduction took place, and having weighed it again in vacuo, I found that it was always of its primitive weight, at least to within o'002 gramme.

The sulphate of siiver employed in the first series was prepared by the action of sulphuric acid on nitrate of silver. The salt employed in the second series was prepared by the direct action of silver on sulphuric acid. Finally, for the third series, I made use of the sulphate obtained by crystallising the preceding salt in water acidulated with sulphuric acid.

Numerical order.

II.

{CHEMICAL, NEWS,

[blocks in formation]

Jan. 11, 1862.

100.000 parts of

Silver yield
Metallic Silver

First Series.

grammes.

grammes.

[blocks in formation]

67200

60·251

416945

41.692

67197

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][subsumed][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][subsumed][merged small]

On the Oxalates of Iron, by EMERSON REYNOLDS, Assistant Chemist to the Dublin Chemical Society. THE attention of chemists has recently been so much directed towards the vast field of organic research, that inorganic chemistry has been comparatively neglected, and errors which in former days would have been soon found out, now remain unnoticed until accident brings them to light. The object of the present paper is made in the expression of the formula of the protoxalate twofold,-first, to correct a mistake which has been of iron; and, secondly, to point out the theoretical considerations involved in certain reactions of the protoand per-oxalates of iron.

For many reasons, it will be more convenient to consider them under their respective heads.

99 to

1. On the Correct Formula for Oxalate of the Protoxide of Iron.—A short extract from the ComptesRendus appeared in the CHEMICAL NEWS (No. 48, vol. ii.), noticing a paper by Dr. Phipson "On a New Combination of Oxalic Acid with Protoxide of Iron,' which the author assigned the formula FeO,4C2O3, calling it "quadroxa'ate of iron." Dr. Croft, of Toronto, it appears, criticised this paper in the Canadian Journal of Science, but his comments upon it, as well as the results of his experiments, instituted with a view to disprove some of the statements made by Dr. Phipson, have been reproduced only a few weeks ago in the pages of the cation from Dr. Phipson appeared in No. 8o, vol. iii. of CHEMICAL NEWS. In June last an original communithe CHEMICAL NEWs, in which he gives the results obtained by the combustion of the salt with oxide of copper. From the data thus found he now calculates the following formula, FeO, 3C2O3 + 4HO, which differs from the one before proposed in representing the salt as being a teroxalate, with four equivalents of water, instead of the anhydrous quadroxalate. I think it will be apparent, from what I have said, that Dr. Phipson did not see the notice of his paper by Dr. Croft, at least before he wrote the second one; and, again, that Dr. Croft had not seen Dr. Croft, therefore, has shown that Dr. Phipson was not correct the second paper before writing his own. in calling the salt "quadroxalate of iron;" but what I wish to prove is, that it is not a teroxalate of iron, with

1 See CHEMICAL NEWS, No. 106, vol. iv.

NEWS

1862.

four equivalents of water, but a protoxalate, with two equivalents of water, being represented thus:FeO,C2O3+2HO. Now, it is to be remembered that Dr. Phipson must have first estimated the oxalic acid by the loss sustained on igniting a given portion of the salt in air, calculating all the volatile matter as oxalic acid; but, in the second instance, he says, that the oxalic acid was determined by combustion, as carbonic acid and the water was directly estimated. It is evident that we must be very cautious in contradicting his later formula without sufficient evidence to ground our contradiction upon.

About a year and a-half ago, in the course of some experiments, I had obtained a solution of a per-salt of iron in stong alcohol. On adding oxalic acid, no precipitate was observed at first, but after being exposed to ordinary light for a few days, a yellow crystalline deposit was observed; an examination of the minute precipitate was sufficient to convince me that it was a compound of oxalic acid with protoxide of iron. Not finding any information on this subject in the ordinary" Handbooks," I referred to Berzelius' Traité de Chemie, and found that Döbereiner had noticed this remarkable reaction, which took place under the influence of the solar rays, many years ago. Following up the subject, without any ulterior object beyond wishing to obtain some information respecting these salts, it occurred to me that the power which the actinic rays possessed of reducing the per-oxalate of iron to the state of protoxalate might be made use of in a photographic point of view. It would be out of place for me to speak now of the modus operandi of my process for printing by light based on this reaction, as a notice of it has already appeared in a late Number of this Journal. It is sufficient to say that the results of the experiments which were necessary in working out the process have given me the means of establishing the correct formula for oxalate of the protoxide of iron. In the first place, then, the results of the analyses on which Dr. Phipson bases his original view regarding the composition of the salt are as follows:

[merged small][merged small][merged small][ocr errors][ocr errors][merged small][merged small][merged small][merged small]

The numbers I. II. III. refer to the method adopted for preparing the salt used, as well as to the number of the experiment.

It being necessary for me to ascertain what was the nature of the reaction which takes place between the oxalate and ammonio-nitrate of silver, I found that the method pursued in the following experiments enabled me to determine the amount of oxalic acid contained in the salt, with the requisite accuracy.

225 grains of the oxalate of iron (1.) were taken and placed in a glass vessel; a known excess of ammonionitrate of silver was then added, upon which the mixture immediately became black, but no gas was evolved; after prolonged digestion it was then filtered, and the insoluble matter collected, dried, and weighed, when its weight was found to be 23.472 grains.

Now, if we consider that 22'5 grains of the oxalate are capable of affording 100 grains Fe2O3, and that a relative equivalent of silver weighs 13'5 grains, the sum 23'5 grains corresponds very closely to the experimental number 23'472. Therefore, we might conclude that one equivalent of oxide of silver yields up its oxygen to two equivalents of protoxide of iron, which are thereby converted into one atom of sesquioxide. This view is confirmed by actual experiment.

The filtrate from the insoluble residue was now taken, and nitric acid added until the liquid had a very slight but distinct acid reaction. In this way, the oxalate of silver held in solution by the excess of ammonia was thrown down. The precipitate, when collected and dried, was found to weigh 37.88 grains, which corresponds to 39.81 per cent. of oxalic acid contained in the iron salt.

The remaining two samples of the oxalate were treated in exactly a similar manner; the results obtained, which correspond with those of Döbereiner and Rammelsberg, are given in the following tabular form, in which, for the sake of comparison, the formula FeO, CO3 + 2 HO is doubled :—

[blocks in formation]

180

100'00

[ocr errors]

100 100'00

As I before remarked, the oxalic acid was calculated from the loss. If, however, we compare the quantity of protoxide of iron found with that obtained by other chemists, we may safely infer that Dr. Phipson has, in every instance, calculated the Fe 0, obtained as FeO instead of Fe2O2, and, as a consequence, found only half the real quantity of FeO, as already pointed out by Dr. or, viewing oxalic acid as dibasic, Croft. I merely draw attention to it here, as it will be necessary to bear it in mind hereafter.

The water was determined by difference. On carefully considering the conditions under which the above numbers were obtained, I think it is perfectly evident that the true formula for the salt is

FeO, CO +2 HO

Fe2O2, CO+4 HO.

On referring to Dr. Phipson's last paper, v following numbers as the results of two an yellow salt:—

[ocr errors]

1.

19'41

Protoxide of iron
Oxalic acid (by diff.). 591
Water (direct.).

For the determination of the protoxide of iron, and other experiments, three modes of preparing the salt were had recourse to. 1. By precipitating ferrous sulphate with oxalate of ammonia. 2. By precipitating ferrous sulphate with oxalic acid (Vogel). 3. By treating solution of ferrous sulphate with normal oxalate of potash (Rammelsberg). Each of the salts produced in the above manner was washed and dried thoroughly, when the following results were obtained on analysis:- This composition corres

FeO

Theory. 40'00

I.

39.60

11.

39.00

[ocr errors][merged small]

2 An excellent résumé of the state of our knowledge with regard to the combination of the oxides of iron with oxalic acid will be found in Gmelin's "Handbook of Chemistry."

3 CHEMICAL NEWS, No. 105, Vol. iv. p. 304.

formula

21

[ocr errors][merged small]

These results are obvious with my own conclusions; th for us to account, if possible, for

« AnteriorContinua »