Chemistry. XXXE 
which Berzelius has given us the analysis. Seleniate of barytes 
he found composed of 
Selenic-acids ...: 3. °100°0. .. 000 eed e700 
Barytes-. 040400086, V37:7 - 1:00 0 Senme reO 
The constituents of seleniate of soda, according to his analysis, 
were, 
BodaMduvwsese f daiBinlas over -.. 4000 
The equivalent for selenic acid derived from the first of these 
salts is 7, which corresponds with the weight of an atom of sele- 
nic acid derived from the choride of selenium. The equivalent 
number derived from the second salt is 7-267, which corresponds 
with the weight of an atom of selenium derived from the quantity 
of oxygen indicated by the chlorine with which it had been in 
combination. As we have no means of determining which of 
these two results is the most accurate, the proper mode of pro- 
ceeding, in the present state of our knowledge, seems to be to 
take the mean of the two as the true number. On that supposi- 
tion 5°125 will be the weight of an atom of selenium, and 77125 
the weight of an atom of selenic acid. ~ 
Selenium then approaches arsenic in the weight of its atom. 
It constitutes another exception to the law which Cirsted has 
endeavoured to establish, that acidifiable bases always combine 
with a great quantity of oxygen compared to their own weight ; 
while alkalifiable bases unite with a small quantity. Indeed 
nothing can be more hazardous than the establishment of general 
laws in chemistry from the very imperfect inductions which the 
present very limited knowledge which we possess enables us to 
make. In a few years, the discovery of some new substance 
which spurns our laws, is sure to overturn all our fine constructed 
fabric, and to give us a mortifying proof of how very inadequate 
judges we are of the general laws by which the constitution of 
the world is maintained. 
Selenium, like sulphur, phosphorus, and carbon, has the pro- 
perty of uniting with hydrogen, and forming selenuretted hydrogen 
gas. Berzelius obtained this gas by fusing together potassium 
and selenium, and treating ¢he selenuret with diluted muriatic 
acid. This gas has the smell of sulphuretted hydrogen. It acts 
with great violence upon the throat and fauces, producing symp- 
toms of rather an alarming nature. It is more soluble in water 
than sulphuretted hydrogen gas. The aqueous solution precipi- 
tates all the metals, and the colour of the precipitates is black or 
brown, except those of manganese, zinc, and cerium, which are 
flesh-coloured. The black and brown precipitates are selenurets, 
the red are hydroselenurets. Selenuretted hydrogen gas is 
readily decomposed by the concurrent action of water and air, 
There is reason to conclude, from the analysis of this gas by 
