156 REPORT— 1871. 



with great advantage; but it must be given for this purpose in very different 

 proportions to those in which it is now commonly i^rescribed. The best 

 plan would be to administer it by inhalation until a decided influence over 

 the motor action is manifested. In pharmacy it would be convenient to 

 keep the nitrite in the pure and simple state, leaving the dilution of it, in 

 alcohol, to the judgment of the physician. 



NlTEATE OF AmTL. 



Nitrate of amy!, C, H^^ NO3, is a pale amber-coloured fluid, of not very 

 agreeable odour. It has a specific gravity of 0-992, a boiling-point of 138° C. 

 (280° r.), and a vapour- density of 66°. It is made by acting with strong 

 nitric acid, 30 grms., on urea nitrate, 10 grms., adding afterwards 40 grms. 

 of pure amylic alcohol. I am again indebted to Mr. Ernest Chapman for 

 a specim.en of nitrate of amyl, freed as far as possible from nitrate of butyl, 

 from all trace of which it can with difficulty be separated. 



In the nitrate of amyl we have a substance differing chemically from 

 nitrite of amyl in ha\'ing an additional equivalent of oxygen, and differing 

 physically in that it is heavier and of higher boiling-point. It enters the 

 body readily by aU channels, and in its general effects it agrees with the 

 nitrite, except that a longer time is required for the development of sym- 

 ptoms from it, and a longer time is demanded for the process of recovery from 

 its influence. The quantity necessary to produce decisive results is the same 

 as with the nitrite ; but the nitrate is not so pleasant a substance to admi- 

 nister, and when administered by inhalation is not so conveniently applied. 

 "Whether the nitrate of amyl has any real advantages over the nitrite is a 

 question on which I would prefer not to speak at length, until larger oppor- 

 tunities than I have yet had of proving it have been afforded me. 



SULPHO-TTREA. 



In my last Eeport I treated on the physiological properties of certain of 

 the organic sulphur compounds, viz. sulphur alcohol, mercaptan, and sulphide 

 of ethyl. Recently a very curious and interesting sulphur compound has 

 come before me for experiment ; I mean a crystalline substance known by 

 the name of sulpho-urea. Sulpho-urea was first made, I believe, by Prof. 

 Ueynolds, and it has since been produced in London, in Dr. Thudichum's 

 laboratory, by Mr. Charles Stewart, to whom I am indebted for the speci- 

 mens with which I have conducted my researches. Unfortunately the 

 manufacture is difficult, owing to the necessity for many recystallizations, so 

 that I have only been able to work with six drachms ; but the results, as 

 far as they go, deserve notice. Mr. Stewart has kindly given me the fol- 

 lowing note in regard to the preparation of sulpho-urea : — 



" About a kilogram of pure ammonium sulphocyanate is dried at 100° C, 

 powdered, and dried again. Slight loss by sublimation occurs. AVhen per- 

 fectly dry, it is heated gradually by a paraffin bath to 170° C, and maintained 

 at that temperature for two hours. The mass is then allowed to cool to 

 110° C, treated with one and a half times its bulk of boiling water, decanted 

 from a small quantity of black matter (it is impossible to filter it, as it de- 

 stroys paper filters), and set aside to crystallize. The crystals arc long, fibrous, 

 satiny needles ; they are drained, pressed strongly in Hessian cloth, and 

 purified by recrystallization from water. The product is then dissolved in 

 boiling alcohol, filtered from a little canmonmm sit?^^/i«^e which remains undis- 

 solved, and set aside to crystallize. Two more crystallizations from alcohol 



