.7. P. Cooke— New Modr nj Mnii^.Udhvj llf/drir Sulphidr. 427 



composition here obtained for the Grafton triphylite renders it 

 almost certain thai this is the correct formula of the mineral. 

 This work was conducted in the Sheffield Laboratory under the 

 supervision of Professor O. D. Allen, to whom I wish here to 

 express my thanks. 



Art. XLVIL— On a new Mode of Manipulating Hydric Sulphide : 

 by Josiah P. Cooke, Jr., Erving Professor of Chemistry and 

 Mineralogy in Harvard College.* 



In chemical laboratories, where instruction m q 

 analysis is given to large numbers on the class system, the use 

 of hydric sulphide gas as a reagent is attended with grave 

 inconveniences. These evils can in great measure be avoided 

 by substituting for the gas a solution of the reagent in water, 

 saturated at the ordinary temperature and pressure of the air ; 

 when, as is well known, one volume of water dissolves about 

 3-4 volumes of the gas (measured at 15° C. i 

 meters). Such a solution was for a long time used in the labora- 

 tory of Harvard College. It was prepared in a long series of two 

 liter bottles connected by glass tubes in the usual way, and the 

 solution was kept in the laboratory in a large tubulated glass 

 flask, from which it was drawn by the students, as occasion 

 required. This solution answers almost every p • 

 which the reagent is used in the ordinary course of qualitative 

 analysis, and the few conditions under which it does not give 

 voided to reover, in ease of 



■ m and promptness of effect it has all the adva 

 a liquid reagent; and the only incon vem. 

 is an occasional evaporation of a solution, which the 1 1 

 the reagent may render necessary. Of course a solution oi 

 hydric sulphide "is liable to oxidation, and soon becoi 

 in contact with the air ; but this change <» 



_ to the neck of the flask (in wmrl. th^Mitioniskept) 

 by means of a rubber stopper, a glass tube dipping 

 liquid, and connecting this tube with one of the vents oi illum- 



inating gas in the laboratory. 



For quantitative work, and for die p 

 products, when considerable quantities of metallic - 

 must be precipitated, a solution of hydric suiphid, a 

 under theordinary pressure of the air, is mconyen e n 

 and two years since we described a simple > method by *hrch a 



with the 



- laboratory appliances. A heavy gla 



