1818.] new Alkali and a new Metal. 293 



tion, ending in a catarrh, which continues for a considerable 

 length of time. I am still suffering from having breathed, some 

 days ago, a bubble of selenuretted hydrogenous gas, no larger 

 than a small pea. Scarcely had I perceived the hepatic taste 

 in the fauces, when I experienced another acute sensation : I 

 was seized with a giddiness, which, however, soon left me, and 

 the sensibility of the schneiderian membrane was so far destroyed 

 that the strongest ammonia produced scarcely any effect upon 

 the nose. 



Selenium combines with the alkalies, both in the humid way 

 and by fusion ; these combinations are red. The selenurets of 

 barytes and of lime are also red, but they are insoluble. It also 

 dissolves in melted wax and in the fat oils ; the solutions are 

 red, but have no hepatic odour. There exist also selenuretted 

 hydroselenurets of the alkalies and of the earths. 



Selenium dissolves in nitric acid by the assistance of heat ; 

 the solution, evaporated and sublimed, yields a mass crystallized 

 in needles, which is a pretty strong acid ; it has a pure acid 

 flavour, and forms specific salts with the alkalies, earths, and 

 metallic oxides. The selenic acid is soluble in water and in 

 alcohol ; its combinations with potash and ammonia are deli- 

 quescent ; the latter is decomposed by fire, water is given out, 

 and the selenium is reduced. The selenates of barytes and of lime 

 are soluble in water. The selenic acid mixed with muriatic acid 

 is decomposed by zinc, and the selenium is precipitated in the 

 form of a red powder ; by sulphuretted hydrogen gas an orange- 

 yellow precipitate is formed. 



The above contains a concise exposition of the characters of 

 this interesting substance. With respect tc its origin, it is 

 evident that it proceeds from the pyrites of Fahlun, where, 

 according to the observation of M. Gafm, its odour may be often 

 perceived when the copper ore is roasted. The pyrites from 

 which the sulphur of Fahlun is extracted is combined with 

 galena, and it is probable that this contains selenium in the form 

 of selenuret of lead. 



Article XII. 



Analyses of Books. 



Transactions of the Horticultural Society , Vol.11. Part VI. 



ALTHOUGH many of the papers contained in these Transac- 

 tions are on topics of mere practical utility, and, therefore, 

 scarcely adapted for our journal ; yet there are others of a more 

 scientific nature, or on subjects of more general interest, and 

 as comprising the labours of a very active and intelligent body 



