MISCELLANY. 

Cause of Decrepitation ; by M. Baudrimont. — Most authors on this sub- 
ject have attributed decrepitation to the vaporization of water contained 
between the laminae which compose the substance operated upon. This 
opinion not appearing- to me well founded, I dried at a low temperature 
and by various means, different anhydrous substances capable of decrepi- 
tation, but found that notwithstanding the most perfect desiccation, they 
still decrepitated when suddenly heated. The tendency of the decrepi- 
tating body to a separation of its parts in the direction of its cleavage faces, 
leads me to the following conclusion : that decrepitation is owing princi- 
pally to the bad conducting power of the several substances, the outer 
layers expanding by heat, without a corresponding internal expansion, 
and consequently splitting off with a kind of explosion. There are in- 
stances, however, in which the substance is volatile and for this reason 
decrepitates ; but this is not in general the case with decrepitable sub- 
stances. 
American Joarnal of Science and Arts — and IS Institute JSo. 158. 
On Donium, a new substance discovered in Davidsonite ; by Mr. Thomas 
Richardson. — The mineral Davidsonite was discovered by Dr. Davidson, 
of Aberdeen, in a marble quarry near that city. An analysis of it by Mr. 
T. Richardson, proves it to be composed of Silica and a base which Mr. 
R. supposes to be an oxyd of Donium. This oxyd is distinguished from 
the alkaline and earthy bases, and from several of the metallic ones, by 
the green precipitate which it gives with the sulph-hydrate of Ammonia; 
and its solubility in the caustic alkalies, and in carbonate of Ammonia, 
the light brown precipitate thrown down by sulphuretted hydrogen, and 
the green given by sulph-hydrate of ammonia, distinguish it from all the 
others. 
The name Donium is a contraction of Aberdonia, the Latin name of 
Aberdeen, near which place Davidsonite occurs. 
Bee. of Gen. Sc., June, 1836. 
Since the publication of Mr. Richardson's paper descriptive of Donium, 
Dr. Bause, of Penzance, has announced that he has been examining for 
sometime a new oxyd which turns out to be identical with that of Donium. 
We may soon expect a complete account of Donium and its compounds, 
from Dr. Thomson of Glasgow. 
Ibid and Ath. No. 452, June 25, 1836. 
VOL. II. — NO. iv. 44 
