144 ^^ VlTROUS ETHER. 



tlie common temperature. I liave seeh^ says Mr. Giivton, 



Iblack iJ^lass bottles, into which ronrentrate<l sulphuric aci(i 



had been put, perforated with several holes in the course of a 



few flays; which, bein^ largest interiorly, exhibited there 



white, sUlvy excrescences, formed of the acid united with 



T^. J the soluble earths of th6 elass. But all elass susceptible of 



This a good ... . . ^ . i p • . • 



test. alteration m the an* is not of so defective a composition ; so 



that to form a judgment of it, the acid must be digested 



upon it, and the heat carried so far as to raise the acid in 



vapour. When this is done, it will leave untouched only 



well made and well reflned glass, whatever be its nature, 



transparency, or colour. 



But may be Sulphuric acid then fulfils all the conditions required for 



neglected from a test. I foresee liowever, that this chemical instrument 



^^^* will frequently be ne<^lected, from fear of the accidents, to 



which they may be exposed, who are not in the habit of using 



it with caution. This has led me to substitute an agent 



equally powerful, that may be procured more easily, and 



employed without any danger. 



Easy mode of This ageiit is sulphate of iron, the green copperas of the 



ascertaining its shops. After having put into a small Hessian crucible, or 



sulphate^/ any other of stoneware, shps of the glass to be examined, 



iron. either alone, or comparitively with others, let the crucible be 



nearly filled with this sulphate coarsely powdered. It may 



tben beset on the fire, and kept there till the metallic salt 



has acquired a red colour. When the glass is grown cold, 



it only requires to be immersed in water, which will shovr 



whether it will be altered, and in what degree. 



This process is not expensive, requires no^pparatus, and 



is in eveiy one*s power ; and the results I have obtained 



appear to me to leave no doubt of its advantage. 



XVII. 



Iteport on a Paper on Nitrous Ether, read to the Institute the 

 4th of August, 1806, by Mr. Thenard, Professor in tJie 

 College of France. By Messrs. Guyton, Vauquelin, 

 and Berthollet*. 



Various eibcrs. ^ ARIOUS kinds of ether have been formed by the ac- 

 tion of some of the acids on alcohol. Volatility, inflamraa- 



• Annales de Chimie, vol. Ixi, p, 282, March, 1807. 



bility, 



