Chemical Science, ' 209 



M. Planche has observed, that when sulphate of copper is dis- 

 solved ill wine vincg\ir, for the ])urj)ose of ])reparin^ a corrosive 

 liquid to be applied to corns on the feet, that the tartaric acid pre- 

 sent in the vineg-ar displaces the sulphuric acid from a part of the 

 salt, an^ an. insoluble acid tartrate of copper is produced. 

 .iHvir.'i.*..- • M'i; -'i. ..' .,••■■■ ^" ■. • : ■■(■-; ;'...•• 



2liu^$eparatton of Arsenic from Nichd or Co6«Z<.--*-The following 

 process by M. Woehler seems among the best of those intended 

 for freeing nickel or cobalt from arsenic in the dry way. • It is 

 founded upon the circumstances that many alloys, when heated with 

 sulphuret of potash, become changed into a mixture of sulphurets, 

 and that sulphuret of arsenic is very soluble in sulphuret oi^>otash. 

 One i)art of kuplernickle, fused and reduced to fine powder, is to be 

 mixed with 3 parts of carbonate of potash, and 3 parts of sulphur, in a 

 covered Hessian crucible. The heat is to be gradually raised to 

 redness, and until the mass is just entering into fusion, and by no 

 means so highly as to fuse the sulphuret of nickel which is formed. 

 When cold, water is to be added, which will dissolve the sulphuret 

 of potash, and leave a yellow crystalline powder, which is sulphuret 

 of nickel, retaining, perhaps, a little copper or cobalt, but no arsenic, 

 if the operation has been well performed. When, however, the 

 object is to have the nickel perfectly pure, it should be fused a 

 second time with sulphur and potash. 



The method of freeing cobalt from arsenic, is the same as for 

 nickel ; but it is then necessary to perform the operation a second 

 time. The cobalt (that of Tunaberg) has never been perfectly freed 

 from arsenic by one operation, but has never retained any after the 

 second. — Archiv filr BergbaUy 1826, p. 186. 



22. Compounds of Gold. — According to late experiments of Dr. 

 Thomson, peroxide of gold consists of 



1 atom gold 25 



3 „ oxygen a,i.i,.<u - 



28 

 and is consequently a teroxide. Muriate of gold consists of. 



,3 , atoms muriatic acid 9.25 ,. 



, X.i .». per oxi.cl^.,9f gftl4 ,,,,.. 28 . 

 5 „ watei^;^ I *w'^^l#Hb».-«i«:>W-.fty :^ • ^25 



/ < i 11 ' Edin. Jowrntd, p. 1 82. 



23. Chemical 'Re^searches rclaiive to certain Ancieiit Substances.—^ 

 M. Vauquelin has analyzed, i. A poignard blade formed of copper 

 only; ii. A mirror, which was found to consist of 85 parts of copper, 

 14 of tin, and 1 of iron per cent. ; iii. A blue colour found in a tomb: 



JUNE — OCT. 1827. P 



