A dispensatory, or commentary on the phgarmacopoeias of Great Britain.

  • Robert Christison
Date:
1848
Catalogue details

Licence: Public Domain Mark

Credit: A dispensatory, or commentary on the phgarmacopoeias of Great Britain. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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    therefore now preferred by manufacturers. If the commercial salt be purified by a single crystallization, and the sulphuric acid used in the proportion of two equivalents to one of the salt, the full theo- retical quantity of strong nitric acid may be obtained, without any of the frothing up of the materials which has been complained of by some [Maclagan]. According to Pelouze pure nitric acid of full density may be got by distilling the commercial acid previously mixed with four or five times its weight of sulphuric acid.—It may be freed from chlorine by simple distillation, rejecting the first eighth or fourth part according to its original quality [Barreswil] ; but this is more effectually accomplished and at very little cost by previously add- ing to it a little nitrate of silver. Nitrous acid may be entirely re- moved by passing a current of carbonic acid gas through a bottle of the strong and otherwise pure acid kept at a temperature near its point of ebullition [Millon.] Nitric acid is colourless when pure, emits gray fumes of an irri- tating, peculiar odour, and possesses an intensely acid, corrosive taste. It quickly turns the skin yellow, and soon corrodes and dis- solves this, as well as all other soft animal textures. The yellow tint of the skin is indelible except by gradual attrition ; and it may be known by becoming much brighter under the action of ammo- nia, or of soap. The density of the strongest acid is variously stated, but probably 1500 is the densest which can be obtained free of nitrous acid. When impregnated with nitrous acid, however, it may be got so heavy as 1540 or upwards; and it has then a yel- low colour and emits copious orange fumes. The pure colourless acid slowly undergoes decomposition under exposure to light ; oxygen gas is disengaged, and nitrous acid formed, which remains in the fluid, imparting a yellow colour. Its boiling and freezing points vary with the strength. The strong acid concretes at —50°, and boils at 248°; but a boiling temperature decomposes it in the same manner as the gradual action of light. A weak acid parts with a feebly acidulated water in the first instance, when an at- tempt is made to distil it; and when the residuum reaches the density of 1420, it passes over unchanged. An acid loaded with nitrous acid, if exposed to a temperature short of ebullition, parts with nearly the whole nitrous acid in the form of orange fumes, and at length becomes nearly colourless; but complete deprivation of colour cannot be attained without a considerable part of the nitric acid also being discharged. Nitric acid unites readily with water, much heat being at the time evolved, though considerably less than in the case of sulphuric acid. It oxidates most of the metals, dissolves the greater part of them, and at the same time un- dergoes decomposition, nitric oxide gas being evolved, and forming ruddy, suffocating fumes on coming in contact with the atmosphere. It unites with bases, and forms salts, most of them neutral, and many crystalline. It is not hitherto known in any other condition
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