three equivalents of water. If these crystals be heated, with access of air, they undergo decomposition; nitrogen gas escapes, bicarburet of iron and cyanide of potassium are formed.

Cyanogen, it will be perceived, is equal to bicarburet of nitrogen; that is, Cy=N,C,.

This process is, perhaps, the best for obtaining cyanide of potassium ; but, if that substance be left exposed to the air, it absorbs oxygen, and becomes cyanate of potash.

Ferrocyanide of potassium is a delicate test for a persalt of iron. If a drop be added to a solution of that salt, a beautiful prussian blue is obtained. It also throws down most of the metallic salts from their solutions. In such decompositions the two equivalents of potassium are replaced by two atoms of the metal in solution. It is a substance of frequent use in the manufactures.

The equivalent of ferrocyanide of potassium is

Two equivalents of potassium,

One

of iron,

78.4

27.2

Ferricyanide of potassium, or red prussiate of potash, is composed of three equivalents of potassium, two of iron, and six of cyanogen; that is, K3, Fe, Cyб. It is prepared by transmitting chlorine gas through a solution of the ferrocyanide till it will not give a precipitate of prussian blue with a persalt of iron (Graham). It crystallises without water. It gives a precipitate of prussian blue, with a protosalt of iron, or green vitriol. From a solution of the persalt it gives Turnbull's blue, which is of a lighter shade than the prussian.

The equivalent of ferricyanide of potassium is—

Three equivalents of potassium,

117.6

54.4 328.0 156.0

Iodide of potassium is compounded of one equivalent of iodine and one of potassium. It may be prepared by dissolving iodine in a solution of potash till it is neutral. After evaporation, it is necessary to heat to redness (to drive off the oxygen) to convert some iodate of potash, which is formed at the same time, into iodide of potassium. It is soluble in water, and, by evaporation, it yields colourless crystals.

It is used as a medicine, principally as a solvent for iodine itself.

It is a delicate test for some of the metals. If to a solution of acetate of lead a few drops of iodide of potassium be added, a beautiful yellow precipitate of the iodide of lead is formed.

If to a solution of a protosalt of mercury a few drops of iodide of potassium be added, a yellow precipitate is formed, which becomes scarlet.

Other experiments may be made by putting into solution any metallic salts.

Potash, or potassa, is compounded of one atom of potassium and one of oxygen; it is, therefore, the protoxide of potassium. It may be obtained by exposing potassium to dry air, from which the metal absorbs oxygen and becomes potash. That which is found in commerce is a hydrate of potash, containing one equivalent of water, which the greatest heat is not able to separate; it is obtained when a solution of potash is evaporated to dryness. Potash is obtained from the vegetable kingdom, (hence the name, vegetable alkali), and from the soil, especially in warm climates, where it exhales as a salt of potash, (nitre or saltpetre). If to a quantity of pearlash (rough carbonate of potash) in solution an equal weight of quick lime, which has been slaked with water, be added, and both boiled together for half an hour, a decomposition takes place; the carbonic acid of the potash unites with the lime, and forms carbonate of lime, which is insoluble; the potash remains in solution, and may be separated by filtration—the liquid must be evaporated to dryness if the potash be required in a solid state. It is generally run into moulds, and forms the potassa fusa of commerce, in which state it is also used as a cautery in surgery. It seldom happens that this potash is pure, as the sticks generally contain a little carbonate of potash; from which they may be freed by dissolving in alcohol, in which the carbonate and other impurities likely to be present are insoluble.

The pure hydrate of potash is white, hard, and brittle, extremely caustic, and possesses in a great degree the property of abstracting moisture from the air, and running into a liquid. With the addition of a little water it may be crystallised.

It possesses the properties of an alkali in a high degree. It is largely employed in calico-printing, in making glass (especially the flint glass), and soft soap. It is very useful in the laboratory.

If free potash be in solution, it may be discovered by nitrate of silver, with which it gives a dark-brown precipitate. A strong solution of tartaric acid will, with agitation, give a precipitate of bitartrate of potash. The equivalent of potash is

Nitrate of potash, or saltpetre, is compounded of one equivalent of potash and one of nitric acid. This substance is produced in large quantities in India, by the putrefaction of animal matters. It is also a natural

product of the soil, from which it is obtained by washing: but the substance imported is rough nitre, and has many other substances in combination, from which it may be freed by dissolving and crystallisation. It crystallises in long striated prisms of six sides, but without any combined water. There is generally a small quantity lodged between their lamina.

By the application of heat it fuses into a limpid liquid. It is cast into moulds, and has the name of sal prunella. If a strong heat be applied, it undergoes decomposition, in consequence of the destruction of the nitric acid. During this decompostion it is either hyponitrate of potash or potash, according to the quantity and continuation of the heat.

Nitrate of potash contains much oxygen, which it will frequently give off by the application of heat. This oxygen may be used for common experiments, but not where accuracy is required. It is used in the chemical arts and manufactures, in making fulminating powder, and to a great extent in making gunpowder, the composition of which is—

In the solution of nitrate of potash in water, cold is generated. One ounce of nitrate of potash will, by rapid solution, reduce the temperature of five ounces of water 15o.

Its equivalent is

One equivalent of nitric acid,

of potash,

54.0

47.2}

101.2

Chlorate of potash consists of one equivalent of chloric acid and one of potash. This salt is an artificial one, and is prepared by passing chlorine gas into a solution of potash. During this operation, chloride of potassium and chlorate of potash are formed; the latter is separated by crystallisation, being the least soluble of the two. When this salt is heated to redness it gives out pure oxygen gas, which is derived from the decomposition of the chloric acid as well as from the potash. If the heat be sufficient, the acid loses its five equivalents of oxygen, the potash loses its one equivalent, and the residue is chloride of potassium.

EXPERIMENTS.

If a small quantity of chlorate of potash be triturated in a mortar with a small quantity of sulphur, a series of explosions will follow, and perhaps combustion; which effects are produced by the oxygen of the decomposed chloric acid.

Having carefully pounded about six grains of chlorate of potash (by small quantities), mix it intimately with some sugar. If a drop or two

of sulphuric acid be let fall on the mixture, it will be inflamed. Chlorate of potash is useful in the laboratory as a source of obtaining

pure oxygen gas. It is employed in the manufacture of matches which

are ignited by friction.

The other potash salts will be treated of hereafter.

MANCHESTER,

February 8, 1844.

W. W.

A BIOGRAPHICAL SKETCH OF BISHOP RIDLEY,

BY THE REV. JOHN YOUNG, M.A.

THE names of Cranmer, Latimer, and Ridley will ever be dear to the hearts of the lovers of Truth, whatever title they bear among their fellow-men, or to whatever section of the Church of Christ they belong. Successfully they laboured in holy union, and nobly they died in evidence of the verity, and in the defence of that faith for the preservation of which they lived. Their memories are blessed; and, in accordance with the declaration of the immutable Word of God, they will be held in 66 everlasting remembrance."

The justly celebrated Nicholas Ridley, the last mentioned of this distinguished triumvirate, descended from ancestors who were alike prominent among their fellow-men for rank and virtue; yet great as may have been the glory of his family, he rather gave to, than received lustre from it. He was born at the beginning of the sixteenth century, at Tynedale, on the borders of Northumberland, at which place his forefathers had enjoyed honourable distinction for several generations.

During the juvenile days of Ridley, nothing particular occurred in his history which afforded any presage of the extraordinary character he was afterwards to become. The rudiments of the extensive learning to which he subsequently attained, were received by him at Newcastle-upon-Tyne, from which place, in about the year 1518, he was removed by his uncle, Dr. Robert Ridley, to Pembroke Hall, Cambridge. Here his sparkling genius displayed itself, and his close application to his studies, and rapid acquirements in various branches of learning, speedily gained for him distinction among his associates, and the degree of B. A. The honourable mention of his name in the Pembroke College Register, and the particular reference made to his attainments in Greek and Latin, demonstrate the degree of celebrity to which he had already attained.

The stormy period at which Ridley lived, when the Pope's supremacy was acknowledged in the land, and when a general movement in various parts of the world was being made to throw off the yoke of superstition and error, appears to have been eminently adapted to exhibit in an

imposing form, the character of a man who was subsequently to take so conspicuous a part in the transactions which were of vital importance to the Church. Calmly and steadily, as if no commotion existed, young Ridley continued to pursue his academical studies, and acquired such marked reputation, that in the beginning of 1524, the Master and Fellows of University College, Oxford, invited him to accept of an exhibition there. The controversy, to which this circumstance has given rise, between the two Colleges, each being desirous to substantiate their claim to him, has conferred an honour upon him of the most distinguished order, and such as never, by the disputants themselves, could have been contemplated. With unwearied diligence he continued to urge on his way, unmoved and undiverted by the variety of circumstances by which he was surrounded; and from this period he may be traced, advancing with rapid strides to higher degrees, honours, and offices in the University. To this day the walls of the garden at Pembroke Hall bear testimony of his studies there; the walk in which he used to learn and repeat the Epistles of St. Paul in Greek, is known as Ridley's Walk.”

66

The honour which Oxford felt wishful to confer on Ridley, but which he refused to accept, was awarded to him by Cambridge, for in the same year he was chosen fellow of his own college. In the following year he took the degree of M.A., and in the year after, he was appointed by the college, their general agent in all causes relating to the churches of Filney, Soham, and Laxthorpe, belonging to Pembroke Hall.

The care which his uncle had displayed towards him, in placing him at Cambridge, was followed out in the high degree of anxiety which he evinced, that his nephew should participate in the advantages of foreign universities also, and hence, as Mr. Ridley's studies were now directed to divinity, his liberal relative sent him to mingle awhile with the learned doctors of the Sorbonne at Paris, then the most celebrated University in Europe, and afterwards he enjoyed the like privilege among the professors of Louvain.

In July, 1535, or 1536, he first visited Paris, in company with Bishop Tonstal; where he continued to acquire such a knowledge of the theology of the times, as enabled him to judge so correctly concerning it. Thus conducted by the hand of Providence, like another Moses, who was skilled in all the learning of the Egyptians, he passed through the several scenes which were necessary to qualify him to become a leader and captain in the army of the Lord of Hosts.

The fame of Ridley as a preacher and public disputant, together with the remarkable tenacity of his well-stored memory, and his extensive acquaintance with the Scriptures and the Fathers, induced Cranmer, then Archbishop of Canterbury, to appoint him one of his chaplains: and such was the high sense entertained by the Bishop of his chaplain's christian spirit, deep learning, and solid judgment, as to beget a feeling of affection towards him which never declined.

As an evidence of the high esteem in which the amiable Cranmer held him, he, in 1538, collated him to the vicarage of Herne, in East