232 Intelligence and. Miscellaneous Articles. 



supposed that salts after efflorescence are perfectly anhydrous. 

 Having been long convinced that this opinion is not correct, I have 

 made some experiments upon the principal salts which are efflorescent 

 in a high degree. Crystallized sulphate of soda, exposed to the air even 

 when it is not very dry, readily loses all its water of crystallization. 

 Phosphate of soda becomes readily opake without losing its form. 

 After three months' exposure to the air, it contained on the 18th of 

 July, 7*4 of the 1 2 proportions of water, which it contains in its usual 

 state. Reduced to powder, and thinly spread upon paper, it con- 

 tained on the 26th of July 5*65 proportions of water; — again exposed 

 to the air during a hot and dry period, it contained on the 31st of 

 July only 5*65 proportions ; — afterwards exposed till the 2 1st of Oc- 

 tober, the weather having become colder and more damp, it was found 

 to contain 72 proportions of water : some phosphate which had been 

 calcined, absorbed in five days' exposure to the air, nearly half a pro- 

 portion of water. 



Carbonate of soda behaves on exposure very much as the phos- 

 phate : it becomes opake, loses much water without altering its form - y 

 but I have never found it anhydrous after exposure. 



It results from these observations, that some salts completely lose 

 their water of crystallization by efflorescence j but that others retain 

 variable quantities, according to the hygrometric state of the air. I 

 do not assert, however, that the water may not remain in definite pro- 

 portions j it merely appears that in the phosphate and carbonate of 

 soda, which retains a proportion of water of a certain number, — the 

 seventh for example, — differs but little from that which unites the pro- 

 portion, immediately above or below. — Ann. de Chim. xxxvi. 335. 



NATIVE PLATINA. 



A piece of native platina, weighing about 64 grains, has recently 

 been found in the Russian mines at Hijne-Taguilski. Its shape was 

 round, its surface granulated, and in some places it bore a metallic 

 lustre. Its specific gravity being only 16, it must contain the various 

 alloys met with in platina. It is singular that this specimen was met 

 with in digging an argillaceous stratum. — Monthly Mag. Feb. 1828. 



MANUFACTURE OF ULTRAMARINE. 



M. Gay Lussac announced to the Academy that M. Tunel, inspec- 

 tor of gunpowder and saltpetre, had succeeded in the direct formation 

 of ultramarine, and that what he obtains by his process is finer and 

 more brilliant than the natural colour. It was by following the ana- 

 lysis made by M. Clement Desormes, that the inventor accomplished 

 this desirable object. M. Tunel has already been able to supply the 

 public with ultramarine at 25 francs the ounce j the colour having hi- 

 therto been sold for 50 or 60 francs the ounce. He hopes that he 

 shall be able to sell it at a still more moderate price. M. Tunel has 

 thought proper to keep his process secret for a certain time. — Le 

 Globe, Fev.9, 1828. 



HEAT 



