Scientific Intelligence. — CJiemistry. 191 



Of pure White Oxide of Arsenic, 2.135 

 Alum with a base of Potash, 4. 190 



Marine Salt, - - - 13.560 

 Oxide of Iron and Argil, . 0.115 



20 gr. 



If this powder be really used for colouring gold, as I have 

 been assured, the oxide of arsenic, I should think, can have no 

 effect in that way. — M. J. L, Casaseca. 



Note hy M. UArcet — I have several times had occasion to 

 examine the saline composition known under the name of colour ^ 

 which is employed by the toymen for giving to trinket gold the 

 beautiful yellow colour of fine gold. The following is the re-* 

 suit of my analysis in round numbers : 



Saltpetre, 40 

 Alum, 25 



Sea.salt, 35 



100 



I was not aware that any change had been made in the com- 

 position of this mixture. If the powder examined by M. Casa.- 

 seca be now used for colouring gold, it can only have been 

 adopted of late, and since fashion has introduced the taste, and 

 rendered necessary the employment of variously coloured alloys 

 of gold with silver, copper, iron, antimony and platina. M. 

 Casaseca's observations appear to me to be very important, and 

 will, without doubt, induce authorities to adopt measures of ad- 

 ministration for obliging the persons who prepare, vend, or em- 

 ploy the new composition in question, to employ all the neces- 

 sary precautions against the danger arising from the use of a 

 mixture containing so much oxide of arsenic. — Annales de 

 Chimie et de Physique, Mar. 1826. 



MINERALOGY. 



19. Gay-Lussite. — A new mineral, under this name, is de- 

 scribed, and its analysis given in the Annales de Chimie and de 

 Physique for March 1826. It is a hydrated bicarbonate of lime 

 and soda, the following being its constituent parts : carbonate 

 of lime 32.85 ; carbonate of soda 34^.76; water 82.29=100.00; 

 analysed by J. B. Boussingault. It occurs in crystals dissemina- 



