Imatges de pàgina
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28

Miscellaneous-Answers to Correspondents.

he quietly puts it on one side, by saying, "that when the formula of albumen is established beyond doubt, it will be time enough to think of constructing a name expressive of its composition; but whether a new appellation be devised or not, I would always retain the name Albumen, my desire being to retain, as far as possible, names which are associated with the labours of illustrious men," &c. Mr. Newlands calls the above a reply to my question, but most certainly it is nothing of the kind: to me it appears an attempt, and a very poor one too, to get out of a difficulty. If all the bodies, for which Mr. Newlands cannot build up one of his extraordinary names, which it is scarcely possible to pronounce, much less to remember, are to be considered of uncertain composition, and retain their original names; and every substance whose name is associated with its discoverer is to be in the same predicament, we shall have to reconcile ourselves to having two different systems of nomenclature: one, the original, which I imagine will contain the larger proportion of substances; and the other, that euphonious one of Mr. Newlands. Mr. Newlands will thus, instead of simplifying the compli. cated state of the vast subject he has taken in hand, have succeeded in making confusion more confounded.

Until he (Mr. Newland) can construct a new system, not so difficult to remember as the present one, but which, however, must include all bodies, not excepting Albumen, and bodies of such uncertain composition, I think it would be better for him not to grapple with such an extensive subject.-I am, &c.

On the Estimation of Nitrogen.

INQUIRER.

To the Editor of the CHEMICAL NEWS. SIR,-In the Number of the CHEMICAL NEWS for November 2, Mr. Walker takes exception to some remarks of mine, upon a process proposed by him for the Estimation of Nitrogen. regret very much that he should conceive that I have done him injustice; certainly nothing was further from my intention. But I believe it to be the duty (although often an unpleasant one) of all chemists to point out such errors as they may notice in new processes proposed for analysis.

CHEMICAL NEWS,
Jan. 11, 1862.

behaviour of ammonia to a zinc solution. He conducts the ammonia disengaged by treating nitrogenous substances with soda-lime, into a solution of chloride of zinc, and calculates the quantity of nitrogen from the weight of the zinc oxide precipitated. M. Carey Lea also points out the faultiness of the proposed process."

I write these lines with considerable reluctance, as I especially dislike controversy, nor shall I again return to the subject. I am, &c. M. CAREY LEA.

Philadelphia, December 17.

P.S.-An article of mine on the subject of the "Action of Reducing Agents on Nitrite of Ethyl," is reprinted in the same Number above referred to, and by an error of the press, the word "nitrite" has been made "nitrate," both in the heading of the article and in the 2nd paragraph. Elsewhere it is correctly given. Also in the 3rd paragraph, "heated with PtCl," should read “treated with PtCl2.'

MISCELLANEOUS.

Royal Institution.-On Friday, January 17, at eight o'clock, Professor Tyndall will deliver a lecture on "The Transmission of Heat through Gases."

Chemical

Society. The next meeting of this Society will take place on Thursday, the 16th inst., when "On the Simultaneous the following papers will be read:-" Variations of Hippuric and Uric Acids in Healthy Urine," by Dr. Bence Jones; "On the Solubility of Sulphate of Lead in Hydrochloric and Nitric Acids," by Mr. G. F. Rodwell; "On a New Mode of Effecting Chlorine Substitutions," by Dr. H. Müller.

Tobacco Poison. It is considered by the most reliable authorities that the tobacco crop of the whole world amounts to 250,000,000 kilogrammes per annum. Now, Schlosing has found that, taking one kind with another, there is an average of five per cent. of nicotine in the leaves of the plant; it is clear, therefore, that about twelve millions and a-half of kilogrammes of this poison are annually produced. As the specific gravity of nicotine very slightly exceeds that of water, this quantity would fill nearly 100,000 wine barrels, and would give twelve and de-a-half grammes (293 grains) to every man, woman, and child on the globe. As a few drops will produce death, it is probably much within the mark to say that the nicotine from one year's crop of tobacco would destroy every living creature on the face of the globe, if its proportion were administered in a single dose.

As to the point in question, I can only say that it does not admit of an argument. No number of empirical results can avail to support a method which can be monstrated to be essentially erroneous in principle. The accuracy originally claimed for the process, seems now to be virtually abandoned, and it is claimed that it gives good approximate results. Even supposing this to be true, there can be no advantage in bringing forward a plan based on a radical error, when very good approximate results can be obtained for technical purposes, and with much more rapidity, by volumetric analysis as proposed by Péligot.

An opinion has been expressed on this subject, by an adequate and wholly independent authority, and to that I desire, in conclusion, to refer. Messrs. Kopp and Will notice Mr. Walker's process, and not favourably. In their Jahresbericht for 1860, p. 630, they remark:

"J. Walker proposes a method for the estimation of nitrogen, depending upon a complete ignorance of the

1 The mode adopted by Mr. Walker for determining how much oxide of zinc sal-ammoniac is capable of holding in solution, I consider to be altogether fallacions. To test the dissolving power of a very weak solvent, it must always be placed in contact with a large excess of the matter to be acted upon, (especially in the present case, as that is the position which the sal-ammoniac occupies in his mode of analysis), and the amount dissolved be determined. By taking a reverse course, and adding the weak solvent until the whole of the solid matter dissolves, the quantity of solvent necessary is greatly overestimated, and the most discordant results may be obtained, all incorrect. This is well exemplified in Mr. Walker's own determinations, in one of which 6:15 grs. oxide of zine required 450 grs, of sal-ammoniac to dissolve it, and in the other the same quantity of oxide of zinc required 560 grs, of sal-ammoniac. The inaccuracy here involved invalidates Mr. Walker's subsequent arguments.

ANSWERS TO CORRESPONDENTS.

All Editorial Communications are to be addressed to the EDITOR; and Advertisements and Business Communications to the PUBLISHER at the Office, 1, Wine Office Court, Fleet Street, London, E.C.

adopt the views of the writers.
*** In publishing letters from our Correspondents we do not thereb
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 12s., by post, 128. 8d., handsomely bound in cloth, gold-
lettered. The cases for binding may be obtained at our Office, price
Is. 6d. Subscribers may have their copies bound for 2s. 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.

R. A. P. S.-We are unable to furnish the information required.
J. A. Horsley.We think the discussion had better end.
J. A. Davies-Declined with thanks.

Dr. Ballard's communication is unavoidably postponed till the next Number.

J. M C.-You can purchase pure permanganate of potash in beautiful crystals, at a manufacturing Chemist's. Its preparation is attended with some difliculty unless you have a good laboratory.

THE CHEMICAL NEWS.

VOL. V. No. 111.-January 18, 1862.

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minimum

maximum

mean

100'000 : 69:197

100'000 69.209

100 000: 69 203

100'000 69 230

We perceive, then, that with the exception of the proportional relations between silver and chlorine, and silver and sulphate of silver, there is throughout a difference in excess between the figures obtained by experiment and those obtained by calculation according to Prout's hypothesis.

This difference is, for the mean :

In the case of sulphide of silver, or eight times larger than that existing between the minimum and the maximum.

In the case of nitrate of silver, or four times greater than that existing between the minimum and the maximum.

In the case of silver and chloride of potassium 689819 or thirteen and a-half times greater than that between the minimum and the maximum.

In the case of silver and chloride of sodium, or fourteen times greater than that between the minimum and the maximum.

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In the case of silver and chloride of ammonium 77 or six times greater than that between the minimum and the maximum.

In the case of nitrate of silver and chloride of potas55 sium or three times greater than that between 438239 the minimum and the maximum.

In the case of nitrate of silver and chloride of ammonium 1470, or six times greater than that between the minimum and the maximum. *

18

In the case of nitrate of lead 156605, or three times greater than that between the minimum and the maximum.

In the case of sulphate of lead, or twice as great as that between the minimum and the maximum. It is impossible in this résumé to apportion the true value to all the differences, which would be considerable in some cases, but appear small in others.

I will discuss the results of the determinations of five substances. Indeed, it would suffice to demonstrate that Prout's law is inapplicable to two elements in order to upset the hypothesis. These five bodies are silver, nitrate of silver, chloride of potassium, chloride of sodium, and chloride of ammonium.

30

On the Relations Existing Between Atomic Weights.

According to Prout's hypothesis, the proportional relation between silver and chloride of potassium is as 100'000 68'981.

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Let us now examine what causes may vitiate the accuracy of this result. On the one hand there is the means of effecting the determination; and on the other hand there are the impurities in the materials made use of. Gay Lussac's method may introduce a constant cause of error; but, properly used, it allows of the detection in a litre of liquid of the twentieth of a milligramme of silver, which is but the eighty-thousandth part of the weight of the silver used by me in one experiment. After the use which the Mint Laboratories have made of this method for more than a quarter of a century, we may, I consider, be perfectly satisfied as to the results which it furnishes. If, therefore, there is a cause of error, it ought to be sought for in the uniform presence of impurity in the materials. The details into which I have entered to describe the processes by means of which I prepared the materials, will enable any one to judge of the considerable efforts which I have made to guarantee their purity. To obtain chloride of potassium, I put into operation all the powers which the actual state of science permitted me to apply to the preparation of substances in their greatest state of purity.

The very extraordinary concordance between the results furnished by chlorides of very different origins and produced by diametrically opposite means-this concordance, I say, is a better testimony than any possible argument to their purity which is otherwise so difficult to guarantee. Moreover, the agreement which is observed between my determinations and those of M. de Marignac is an additional proof of purity.

What I have just said with respect to chloride of potassium is applicable to chloride of sodium.

The impurities which, against all probability, might be discovered in these two chlorides, would increase their proportional relations. But without denying the possibility of the existence in these bodies of an unknown foreign substance, there is no chemist who, after having attentively examined all the means which I have employed to procure them, would venture to pretend that the enormous and uniform difference observed by M. de Marignac and myself between the calculated and the experimental numbers, can be attributed to the presence of a known foreign body.

Bearing in mind the processes employed by me to procure chloride of ammonium, it is impossible that there could be found in certain specimens of the salt made use of, bodies foreign to the composition of sal-ammoniac

1 Bibliothèque Universelle de Genève, vol, xlvi. p. 352.

CHEMICAL NEWS, Jan. 18, 1862.

itself. Although I have done all in my power to avoid an excess of hydrochloric acid or of ammonia, it may happen that certain specimens contained a very slight excess of acid; but the presence of this latter body would tend to diminish its proportional relations, and all my experiments lead to a more elevated proportional number for chloride of ammonium.

I may add that, if the existence of unknown foreign bodies should raise the proportional number of the chlorides of potassium and sodium, the possible, and even probable, presence of foreign bodies in the silver would diminish this proportion; the effects produced would be in opposite directions, and the chance of augmentation would, therefore, be diminished by one half.

Let us now see if it is possible to reconcile my syntheses of nitrate of silver with Prout's law. I have demonstrated that 100'000 of the metal produced as a mean 157'473 parts of this salt instead of 157 404; there is, therefore, ths of excess over that required by Prout's law. It may be pretended that this excess of weight is due to nitric acid or to water retained by the fused nitrate. I will first recall that I have shown the neutrality of the salt obtained in my experiment, and the absence of tension when it was fused in vacuo. Moreover, this objection falls to the ground in the presence of the direct control to which I submitted the nitrate of silver itself by determining its proportional relation in respect to chloride of potassium.

According to Prout's law this relation is as 100'000 : : 43.823. But I have found, as a mean of three series of experiments, that this relation is as 100'000: 43°878. M. de Marignac has already obtained the same relation as a mean of two series of determinations. But by combining the result of my synthesis of nitrate of silver with the result of my determinations of the proportional relation between silver and chloride of potassium, I arrive at this conclusion, that 100'000 of nitrate of silver are equivalent to 43 883 of alkaline chloride figures, which are almost identical with those found by experiment. There is, therefore, a perfect agreement between the syntheses of nitrate of silver and the determinations of the proportional relation between this salt and chloride of potassium, and a complete disagreement with the numbers calculated for the three bodies according to Prout's principle. The composition of nitrate of silver, whether determined by synthesis or established from its proportional relation in reference to a known chloride, is, therefore, incompatible with Prout's law. It is, therefore, a necessary result that, amongst the constituent elements of this body, two at least, nitrogen and silver, do not obey this principle.

If it is radically impossible to reconcile Prout's hypothesis with the relations which the atomic weights of nitrogen, silver, and the chlorides of potassium, sodium, and ammonium, present one to the other, there is no reason to admit it in respect to chlorine, sulphur, and lead, if even the numerous determinations given in this memoir did not prove in an evident and certain manner that these bodies do not obey Prout's law.

To conclude this long account, it remains for me to state the value of the atomic weights as derived from my researches.

By the calcination of chlorate of potash I found that 100'000 of this salt furnished on an average oxygen

By the action of hydrochloric acid I found it

to contain an average of The mean of these two results is

39'157

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39'151 39'154

2 Bibliothèque Universelle de Genève, vol. xlvi., p. 365.

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39'150 39°156 39'161

74'59

107 943

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border; and generally not extending eastwards more than 500 yards from the verge of the old lake is found the "caleche" or "terra sulitrosa," rough nitrate. Between the pampa and the coasts exist other old sea lakes, on the borders of which "caleche" is also found; but these deposits are of secondary import. The "caleche" is generally found in insulated masses, irregular in shape and thickness, which adds greatly to the expense of working. It is sometimes found with only a few inches of sand over it, but more frequently covered with a hard stone, consisting of sand indurated with salt; this is called "costra," the thickness of which varies from one to ten feet, but averages three feet. The "caleche varies in thickness from one to nine feet, but in general runs from three to four feet; below this exists a soft 16.0371 sand, containing an abundance of crystals of glauberite and small quantities of borates of lime and soda. The strata consist of

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chlorine, according
to my experiments
chlorine, according

to M. de Marignac

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39°13

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from the synthesis of nitrate of silver) of sulphur lead (synthesis of sulphate of lead). lead (synthesis of the nitrate dried in vacuo at 155°). On glancing at the atomic weights of ammonium and of nitrogen, it will be perceived that they differ by 4:02 instead of by 4'00. It necessarily follows that either my syntheses of nitrate of silver are inexact, and that the quantity of this salt produced from metallic silver is a little greater than I have found it (which removes me still further from Prout's law), or else that the atomic weight of hydrogen itself is wrong byths or t of its value.

ths

The results of my researches lead me to think that the error exists rather in the atomic weight of hydrogen than in that of nitrogen.

If this statement, to which I draw with diffidence the attention of chemists, is correct-and this I am about to investigate by performing the synthesis of water by a new method-it results that the basis upon which Dr. Prout established his law has itself no foundation.

Whatever may be the doubt which I hazard in respect to the accuracy of the atomic weight of hydrogen represented by 1, oxygen being 8, there can be no doubt concerning the principle itself. I therefore conclude by saying, so long as recourse must be had to experiment to establish the laws which govern matter, we must consider Prout's law as a pure illusion, and must regard the undecomposed bodies of our globe as distinct entities having no simple relation of weight among themselves. The undoubted analogy of properties which may be observed between certain elements must be sought for amongst other causes than those which are derived from the relation between the weights of their acting masses.

TECHNICAL CHEMISTRY.

On the Production of Nitrate of Soda at Iquique (Peru). As Iquique is the centre of this trade, and to it its present importance is wholly to be attributed, it is thought to be advisable to convey in this report as much information as can be procured as to this article, and in order that such information shall be truthful, the writer has availed himself of the views of several Englishmen at present engaged in the trade.

About from six to fourteen leagues from the coast, and running parallel with it through the province, at an elevation of 3300 feet or thereabout, is the Pampa of Taramugal. This plain or pampa was a sea lake, and the greater part is covered with salt along the western

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When "caleche" is required, the barretero (miner) makes holes in the ground where he expects to find it. If successful, he fills up the holes with coarse gunpowder made on the spot (costing three and a-half dollars per quintal), regulating the charge in proportion to the thickness and hardness of the "costra " and the thickness of the "caleche;" the charge varies from one to eight quintals, and occasionally as much as fourteen quintals; when blasted the whole mass is turned over and mixed. He then proceeds to separate the "costra" and "cora" from the "caleche," throwing aside all the latter that he does not believe to contain more than ten or twelve per cent. of nitrate; it is then broken into smaller lumps, to be conveyed to the "paradas." A refinery of nitrate is called an "Officina," and is generally placed in the centre of the calecheros or nitrate grounds, and consists of one or more paradas; a paradas is a pair of round iron boilers, each holding from 70 to 300 gallons; these are placed together, in rough stonework, with a fire-place between them. At the parada, the acendrador breaks the lumps into pieces about the size of a fist, rejects the inferior pieces, so as to bring the whole to about 25 to It is now thrown into the 34 per cent. of nitrate. boilers with a quantity of water; after boiling some two or three hours, the fondeador (boiler) continually stirring the mass, supposing that the caleche is by that time exhausted, throws out the ripio (refuse), adds more caleche and mother water; and, after boiling some two or three hours, a well saturated solution is obtained; it is then by hand baled into a deposit, from whence, as soon as the mud and salts are deposited, it is baled into shallow coolers, where it crystallizes. The mother water is then drawn off, and the nitrate thrown out to

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This system of making nitrate is the same as was first adopted at the commencement of the trade, and unquestionably well adapted for that early period, having the advantage of being simple, easily understood and worked; yet it is still continued, and the whole system of labour arranged to it. It is almost impossible to conceive a system more rude and more wasteful; and although many exertions have been made during the past ten years, without success, to improve it, yet that want of success has been caused chiefly by the lack of skilled labour in the province; still there is no doubt that it will be superseded, in the course of a few years, by the more refined and complicated apparatus now being introduced. The theory of the process of refining nitrate is this:"Caleche" consists of nitrate of soda, chloride of sodium (common salt), and earthy matter (the other substances present exist in such small quantities that they are overlooked), and as chloride of sodium is very little more soluble in boiling than in cold water, whilst nitrate of soda is comparatively insoluble in cold, but very soluble in hot, water, it is very evident that it is only required to add such quantities of "caleche " to boiling water to procure a strongly saturated solution; the earthy matter, being insoluble, is left with the excess of common salt in the boiler, or the deposit, before it is discharged into the coolers, where, as the liquid cools, it deposits the excess of nitrate of soda, the mother liquor retaining all the salts in solution. Reverting to the customary process of refining, two systems are now being tried, which use steam; in the one (Gamboni's patent) the "caleche" is placed in an inverted semi-cone, with a perforated cover and bottom; through the side a jet of steam is introduced, mother water is thrown on the cover, and the refined nitrate falls through the bottom, and is at once conveyed to the coolers; in the other, steam is introduced to boil the solution; but both promise the same advantages-economy in the make, and a superior

article.

No sketch of the nitrate trade would be complete without some reference to the abuses. In the first place, it is badly based. The merchant makes advances to the saliteros, officineros (makers), of money and goods, on the promise of receiving in return the product of the officina. This advance frequently is used in paying off old debts, or in advances to the labourers. The merchant must still keep advancing barley for the troops, coals and provisions for the labourer, &c., or there will be no nitrate forthcoming. This system trenches heavily upon the merchant's resources, and occasionally leads to losses. The officineros, as a body (with some exceptions), are a reckless set of men, wasteful in their expenditure and careless of their promises. Their arrangements with their labourers are also bad; their principal ones, the barretero, acendrador, and fondeador, being paid according to the product of the parada, recriminations are ever

CHEMICAL NEWS, Jan. 18, 1862.

recurring, and not unfrequently leading to a closing of the works. Another thing must also be noticed-the great amount of adulteration that has taken place within the three past years. Rarely a cargo leaves that is better than 5 per cent., some even 7 to 10, and some samples assayed have shown as much as 30 to 50 per cent. of foreign matter. The adulteration is effected in two ways; in one, white "caleche" is ground and mixed with the refined nitrate,—this is called green nitrate: the other, the powdered "caleche, is mixed into the solution, and at once put into the coolers,-this is dirty nitrate. This is in some measure protected_by_the present state of the trade. Merchants in England purchase from the importer, and get a deduction from him corresponding to the amount of foreign_matter in the article; but as the general sales are made without any deduction. then the worst cargoes are the most profitable to the merchants.

The province has not been thoroughly surveyed; but enough "caleche" has been discovered to yield an increased supply for ages. In May, 1856, there were about 100 officinas at work, with about 250 paradas; but the work is not constant, 240 days is a good year's work. The principal sales of this article are made in Valparaiso, on the usual terms, viz., ore well sacked, not to contain less than 95 per cent. of nitrate placed in the ship's launch outside the surf. The price has been very fluctuating, commencing at 18 reals, rising to 20 reals, falling to 16 reals, and then in four months rising to 23 reals, but taking an average price of 19 reals; 936,719 quintals, with the exchange at 46 dollars, would give 426,402/. 5s. 10‡d. The other salts found in the province are chloride of sodium, biborates of lime and soda, sulphates of lime and soda, magnesian alum, &c. Iodine exists with the nitrate, and throughout the calecheros traces of boracic acid have been found in the water.— From the Report of H.B.M. Consul,

PHYSICAL SCIENCE.

The Divisibility of Matter.

IT is curious to observe how purely conventional are the terms large and small, great and little, and how meaningless they are when they cease to have relation to matters of every-day experience to our senses. They are simply relative, and depend for their significance upon some artificial comparison instituted in our own minds, which has no connection whatever with the absolute amount of substance regarded in the abstract. The same quantity may thus appear very large or very small, according to the way in which it is viewed, and the size of the bodies with which it is mentally associated; thus, a pound of any mineral may seem an insignificantly small quantity to the miner accustomed to deal with hundreds and thousands of tons; the same lump may appear a large cabinet specimen to the mineralogist, whilst, on the other hand, to the natural philosopher engaged in the detection of its various constituents by means of spectrum analysis, and working on thousandths of a grain, this weight becomes an enormous quantity. The same weight of different bodies likewise appears large or small according to the scarcity or commonness of the material; thus, an ounce of diamonds would fall under the first denomination, whilst an equal weight of coal would be looked upon as a very small quantity. If, however, we cease to associate our ideas of any substance with the purely conventional qualities which it acquires by comparison

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