482 Misceltaneou^ ttttelligence. 



not properly a current ; the lava was heavy or porous, or even 

 pumice-like in various parts, and was covered with muriate of am- 

 monia mingled with a small quantity of arsenic and magnesia, and 

 with two other salts of selenium and iodine. — Bui. Univ., B. x. 45. 



14. On the ejflorescent Salts of Volcanic Rocks. — MM. Bischoff and 

 l^oggerath have examined the saline efflorescence of the Terras in 

 the vallies of Brohl and Tormestein, and found them composed 6f 

 18.901 of sulphate of potash, 18.273 of muriate of potash, 43.872 

 of carbonate of potash, and 20.616 of carbonate of soda. Another 

 salt from Brohl gave sulphate of alumina, with a little oxide of 

 iron, magnesia, a little alkali, and muriatic acid. They endeavoured 

 to discover whether these salts existed, previously formed in thie 

 terras ; they found potash, soda, and muriatic acid in the latter, 

 besides the ordinary earths ; the principal part of the alkalies was 

 combined with the earths, the rest with the acids. The formatidrt 

 of the Salts is attributed to the presence of water, and more or less 

 heat. 



15. On the Nitrates of Ammonia and Mercury, by M. Soubeiran. 

 — If ammonia be added gradually to a very weak solution of pure 

 proto-nitrate of mercury, two precipitates are obtained, one of a 

 grey black, and the other white ; the latter being most abundant 

 the nearer the precipitation is to its termination. If thfe precipi- 

 tate be thrown down and removed irt separate portions, the whit^ 

 preparation may he obtained nearly pure ; it is insipid, inodorous, 

 insoluble in hot or cold water. It is not attacked by caustic alka- 

 lies, or by nitric or sulphuric acid. The substance was analyzed 

 with difficulty, and the result was as follows : — 



Protoxide of mercury 92.3 . 4 proportionals 

 Nitric acid . . 5.85 . 1 do. 



Ammonia . . . 1.85 . 1 do. 



100.00 

 The black precipitate always contained portions of the white 

 substance, and when acted upon by nitric acid left the latter undis- 

 solved. M. Soubeiran considers it in its purest state as composed 

 of one proportional of acid, and four of protoxide of mercury. 



The ammoniaco-mercurial deuto-nitrate may be obtained by 

 adding excess of ammonia to a dilute solution of the deuto-nitrate 

 6f mercury. The white precipitate obtained is insoluble in water, 

 but soluble in muriatic acid, from which potash or soda precipi- 

 tates it ; ammonia produces a precipitate in the solution, resoluble 

 in excess of the alkali. Nitric and sulphuric acids partly dissolve 

 it. It is formed of 



Deutoxide of mercury 86.4 . 2 proportionals. 

 Ammonia . . 3.27 . 1 do; 



Nitric acid . . 10.33 . I do. 



Bull, Univ. A. tom. vii. p. 210. 



