1819.] Sulphuretted Chyaxic Acid. 107 
doses, produces similar effects. This salt then, as well as the 
acid, acts in the same way as prussic acid. 
Meconic acid, taken in a dose of from eight to ten grains, 
produces no sensible effect upon young and weak dogs: and the 
original opinion of M. Sertiimer seems to be much better founded 
than the recent assertion that meconic acid is the most violent 
poison among vegetable substances. 
Meconiate of soda, in a dose of 10 grains, produces no sensible 
effect. 
Morphia, in a dose of 10 grains, or even four grains, is 
narcotic in an eminent degree. A dog fell asleep immediately, 
and slept 24 hours without interruption ; but did not die. 
Recapitulation of the Chemical Experiments. 
It follows from the facts stated in this paper: 
1. That we cannot obtain pure sulphuretted chyazate of 
potash, nor pure sulphuretted chyazic acid, when we calcine 
prussiate of potash and sulphur at a red heat. 
2. That it is sufficient to fuse the mixture, if we do not wish 
to push the decomposition further than is necessary for the 
purity of the products. 
3. That we may obtain pure sulphuretted chyazic acid by 
distilling sulphuretted chyazate of potash, mixed with dilute 
sulphuric acid, or still better with phosphoric acid. 
4, That sulphuretted chyazic acid exposed to the sun, or 
placed in contact with the air, allows sulphur to precipitate 
without assuming a red colour. 
5. That the acid, when exposed toa red heat, is decomposed 
into sulphur, prussic acid, and ammonia. 
6. That nitric acid, or chlorine, does not precipitate sulphur 
from sulphuretted chyazic acid, but forms sulphuric acid, and sets 
russic acid at liberty. 
7. That iodine decomposes the acid, and produces hydriodic 
acid. 
8. That sulphuretted chyazic acid has no other analogy with 
meconic acid than that of forming blood red liquids with per- 
oxide of iron and the persalts of iron. 
9. That sulphuretted chyazic acid is an excellent reagent for 
salts containing peroxide of iron; but only when there is no 
excess either of acid or alkali in the liquid. 
10. That sulphuretted chyazic acid is not composed of the 
elements of prussic acid in other proportions united to sulphur ; 
but appears to consist of a chemical combination of prussic acid 
and sulphur ; and the sulphur is the cause of all the singular 
properties of this acid composed of three combustible bodies. 
11. Finally, that the discovery of Porrett should make us 
attentive in manufactures of prussian blue to avoid a potash 
which contains sulphur, or even too great a quantity of sulphate ; 
because it would occasion a considerable loss in the formation of 
the prussian blue. 
