; 
436 On the different Compounds formed by the 
cumstance, that it might retain some sulphuret of potassy 
and I washed it in boiling water; but if the water dissolved 
any of it, it was too small a quantity to be rendered sensi- 
ble by the acetate of lead, which did not blacken the li- 
quor. After these results, I adopted another method of 
analysis; I burned the coal and obtained a grayish cinder, 
which being washed in water afforded some carbonate and 
some sulphate of potass, discoverable by the solutions of 
barytes and of platina. As, therefore, there were in this 
compound some sulphur and some potass, not soluble in 
hot water, it is very natural to conclude, that these sub- 
Stances are fixed in the coaly matter by a real chemical! 
affinity. From all these circumstances, I am of opinion, 
that one part of the alkaline and earthy bases found in the 
coals of wood, &c. may exist in them in a state of strict 
combination. _ 
4. Action of Nitric Acid. 
Five grammes of the coaly residuum were put into a re- 
tort with fifty grammes of nitric acid heated to 32°*. Red 
vapours and carbonic acid were immediately disengaged. 
On applying heat, the action became much stronger, and 
the liquor foamed greatly. When the greatest part of the 
liquid had passed over into the receiver, I poured twenty- 
five grammes more of the acid into the retort: a complete 
solution took place, and the liqnor was of a deep yellow 
orange colour: when concentraied in the retort, I poured 
it into a glass of water; there was precipitated a deep yel+ 
low flocky matter; this was separated by the filter, and 
washed with a-large quantity of cold water. All the waters 
were mixed and evaporated to dryness, so as to drive off in 
a great measure the excess of acid. The residue was treated 
by a smaller quantity of water; by these means, there was 
procured a small portion of yellow floccose matter, partly 
soluble. I first examined the matter dissolved in the water; 
and then the yellow flocky substance. : 
The aqueous solution, separated from its excess of acids 
and from the matter partly soluble, by several successive 
eyaporations and solutions, was of a brown-yellow colour ; 
its taste was acid, bitter, and astringent ; yellow floccules 
were precipitated from it by gelatin. It contained a little 
sulpburic acid, discoverable by-barytes; it is truc, there 
was a flaky precipitate formed by the astringent substance, 
but this was soluble in nitric acid. (i believe that this sul- 
* Centigrade Thermometer. j 
phuric 
