294 Notices respecting New Booh. 



As glass of antimony is much cheaper than it was some 

 years since, there is only one material objection to its use, and 

 that is, that glass of lead is sometimes mixed with, and occa- 

 sionally altogether substituted for it; and their appearance is 

 so similar, that the most experienced eye may be deceived : 

 it is however easy to distinguish these substances by their che- 

 mical characters. I have observed that the insoluble portion 

 of glass of antimony is of a red colour ; but when glass of lead 

 is boiled in a solution of supertartrate of potash, it is very soon 

 rei dered black, and scarcely any of it is dissolved. It is also 

 easily detected by heating it in dilute nitric acid: if the solu- 

 tion contain lead, sulphuric acid will occasion a white preci- 

 pitate in it 



The present process for making tartarized antimony is sim- 

 ple : supertartrate of potash, as already mentioned, contains 

 excess of acid, and when a solution of it is boiled with glass 

 of antimony, the protoxide of antimony is dissolved, while the 

 sulphuretted oxide and silica remain unacted upon. The so- 

 lution thus obtained consists of tartrate of potash and tartrate 

 of antimony, and these combining form a double salt, called 

 tartrate of potash and antimony, or tartarized antimony. 

 Tartarized Antimony, or 

 Tartrate of Potash and Tartrate of Antimony. 



Supertartrate 



or 



Bitartrate 



of 



Potash. 



'2 atoms Acid. 

 1 atom Potash 



Protoxide of An- 

 timony 



Glass of 

 Antimony 



Sulphuretted Ox- 

 ide of Anti- 

 mony, & Silica_ 

 " Qualities. — Tartarized antimony crystallizes with great 

 facility, and the general character of the crystals of this com- 

 pound is that of an octahedron with a rhombic base *. 



The crystals of this salt are colourless and inodorous, but 

 have a styptic metallic taste : on exposure to the air, they ef- 

 floresce slightly, and become opaque. When heated with 

 carbonaceous matter this salt is decomposed, and metallic an- 

 timony is obtained. It is soluble in about fifteen times its 

 weight of water at 60°, and twice its weight at 212°. The 

 aqueous solution decomposes spontaneously after it has been 

 some time prepared. It is insoluble in alkohol. 



* In the original a d'agram of the crystal as usually occurring is here 

 given ; with its cleavage and measurements. For the crystallographical 

 illustrations in this work, Mr. Phillips acknowledges his obligation to 

 Mr, Brooke. 



" Compo- 



