126 BBOF. FEBBIER ON KNOWING AND BEING. 



'- ' instinct, to be shunned. "Would Professor Terrier, who evidently 

 " reads Greek — not at all a necessary accomplishment in a Scotch 

 " Professor of Moral Philosophy — perhaps be so kind as work out 

 "for us an elegant exposition of the philosophy of Plato in its ptrinci- 

 "ples and its applications t " Such a work as that suggested in the 

 part of the quotation italicised, is still a desideratum ; to undertake 

 it, would be a task not unworthy of the most brilliant genius ; and 

 we do not need to look beyond the " Institutes " for proof that Pro- 

 fessor Perrier possesses in a high degree the principal qualifications 

 requisite for executing it successfully. 



ON THE HYDRATE OP HYDROSULPHUPvIC ACID. 



BY HENRY CBOFT, D.C.L., 



PROFESSOR OF CHEMISTRY, UNIVERSITY COLLEGE, TORONTO. 



Mead before the Canadian Institute, Dec. 1st, 1855. 



Very little is known with regard to the combination of water with 

 sulphuretted hydrogen, although its existence has been pointed out 

 by "Wohler. Its excessive instability at the ordinary temperature 

 and pressure, renders it impossible to ascertain its formula, which is 

 of considerable interest, inasmuch as crystalline hydrates of the hy- 

 dracids are almost, if not entirely, unknown. 



"Wohler obtained the compound in two ways, firstly from liquid 

 hydrosulphuric acid, which had been formed in the usual manner by the 

 spontaneous decomposition of the bisulphide of hydrogen in a closed 

 tube. Among the crystals of sulphur he observed small colorless 

 crystals, which could scarcely be any thing but the hydrate. The 

 tube exploded on being brought into a warm room, the crystals rapidly 

 disappearing with evolution of gas. 



Secondly, by exposing a mixture of alcohol and water, of such 

 strength as not to freeze at eighteen degrees below zero, to a freezing 

 mixture capable of producing this degree of cold, having previously 

 saturated it with well-washed sulphuretted hydrogen, an icy cry- 

 stallization was produced, -which vanished on the least rise of tempe- 

 rature, gas being rapidly evolved. The crystals could not be kept 

 when enclosed in a tube, but reappeared as often as it was exposed 

 to a temperature of 18°. The same results followed when hydrated 

 acetic aether was employed. 



"Wohler thought that he once detected octohedral crystals.* 



* Annalen der Cheraie und Pharrnacie, B., 82. 



