54 REPORT — 1841. 



ammonio-chloride by a mixture of aether and alcohol. From the metallic platinum 

 which remains after the ammonio-chloride is heated to redness, the quantity of nitro- 

 gen is to be calculated. 



We have repeated all the experiments of Dr. Brown on the production of silicon 

 from paracyanogen, but we have not been able to confirm one of his results. What 

 pur experiments prove is, that paracyanogen is decomposed by a strong heat into ni- 

 trogen gas, and a residue of charcoal, which is exceedingly difficult of combustion. 



Neiv extemporaneous Process for the Production of Hydrocyanic Acid for 

 Medical Use. By Robert D. Thomson, M.D. 



The importance of prussic acid as a remedial agent in spasmodic diseases, such as 

 hysteria, chorea, &c., has induced the author to bestow much attention upon the pro- 

 duction of this acid, so as to obtain it always of uniform strength. He has accord- 

 ingly subjected to trial all the processes which have been recommended in this coun- 

 try for the formation of prussic acid, and not finding them in all respects satisfactory, 

 proposes the following process as less liable to objection than any of the preceding. 

 The first step consists in forming a pure cyanide of lead. This object may be effected 

 in various ways, either by precipitating acetate of lead by hydrocyanic acid as pre- 

 pared from the ferrocyanide of potassium and sulphuric acid, according to the pro- 

 cess of the Edinburgh Pharmacopoeia, in a stoppered bottle, or by distilling from the 

 mixed materials into a Wolff's bottle, containing a solution of acetate of lead. In 

 either case a definite compound of cyanogen and lead will be obtained, which is to be 

 carefully washed and gently heated. Care should be taken that the water in which 

 the acetate of lead is dissolved is perfectly pure. Distilled water will frequently pre- 

 cipitate acetate of lead, owing to the greater or less quantity of carbonate of ammo- 

 nia contained in rain-water. It may be removed, as has been pointed out by Prof. 

 Liebig, by adding to the water, previous to distillation, a few drops of sulphuric acid, 

 or a few grains of alum. 



The cyanide of lead having been properly washed and dried, the next step in the 

 process consists in decomposing it by means of sulphuric acid. In order to obtain 

 an acid of the strength of the acidum hydrocyanicum dilutum of the London Pharma- 

 copoeia, or containing about two per cent, of absolute acid, the following formula will 

 be found convenient : — 



Take 46'36 grains of cyanide of lead, 



2 fluid drachms of dilute sulphuric acid (London Pharmacopoeia), 

 6 fluid drachms of pure distilled water. 

 Introduce the cyanide of lead into a stoppered bottle ; mix the acid and water in a 

 glass vessel ; allow the mixture to cool, and then pour it upon the cyanide of lead ; 

 close the stopper and agitate the fluid and salt together. After standing for some 

 time, pour off the supernatant liquor from the precipitated sulphate of lead, and pre- 

 ^erve it in a stoppered bottle. 



This formula is founded upon the circumstance, that dilute sulphuric acid of the 

 London Pharmacopoeia contains, in each fluid drachm, about 9-5 grains of oil of vitriol 

 (S O3 H O). Two drachms will therefore contain 19 grains of oil of vitriol. The quan- 

 tity required for saturating 46-36 grains of cyanide of lead is only 17'4 grains; but 

 the small excess is useful in preserving the acid. 



The advantage of this process, it will be observed, consists in the employment of 

 liquid measures in apportioning the fluids, and in using an acid for the liberation of 

 the cyanogen, which, although added in excess, possess a preservative instead of a 

 deteriorating influence. The author is quite persuaded, from his experience of the use 

 of hydrocyanic acid in medicine, that in spasmodic diseases it is one of the most va- 

 luable agents we possess ; but he is of opinion that the prescriber should watch its 

 action, and repeat the dose until the desired effect is attained. 



On the Composition of Crystallized Diabetic Sugar. By Robert 

 D. Thomson, M.D. 



Having observed various statements in books respecting the crystallization of dia- 

 betic sugar, the author was anxious to test their accuracy by experiment. On the 

 first favourable opportunity the test was applied. An Italian, who had been labour- 



