Hatching of Fishh 381 
by mixing it in fine powder with strong muriatic acid, and 
stirring it until the whole becomes a smooth homogeneous 
mass, of a semi-gelatinous consistence. We notice it here 
merely to remark on the circumstance that an agent in 
which Prussian Blue is insoluble, should be found usefulin 
enabling it to combine with silk, cotton, wool, &c. The 
pure ferro-prussiate of iron is soluble in water, but the addi- 
tion of a smal] portion of muriatic acid immediately precip- 
itates it; wash away the acid by pure water, and the pig- 
ment becomes soluble again; re-acidify, and it re- precipir 
tates. 
22. Test for Morphium.—M. Dublane, a druggist of 
Paris, states that he finds the tincture of nut-gai!s a very 
sensitive test of the presence of morphium in fluids, wheth- 
er it exist free or in combination with acetic or sulphuric 
aka : 
23. Cafeine.—Cafeine is a crystallizable principle dis- 
covered in 1821, in coffee, by M. Hobiquel, whilst search- 
‘ing in it for quina. 
M. M. Pelletier and Caventou ehelieed this substance at 
the same time, but did not complete their researches. M. 
Robiquet read a memoir on this subject to the Société de 
Pharmacie of Paris, which has not been published. [It is, 
however, known to be a new principle, white, crystalline, 
volatile, and slightly soluble. 
24. Hatching of Fish—The Chinese have a method of 
hatching the spawn of fish, and thus protecting it from those 
accidents which ordinarily destroy so large a portion of it. 
The fishermen collect with care, on the margin and surface 
ef waters, all those gelatinous masses which contain the 
spawn of fish; after they have found a sufficient quantity, 
they fill with it the shell of a fresh hen’s egg, which they 
have previously emptied, stop up the hole, and put it under 
a setting fowl. At the expiration of a certain number of 
days, they break the shell in water warmed by the sun: 
the young fry are presently hatched, and are kept in pure 
fresh water till they are large enough to be thrown into 
the pond with the old fish. The sale of spawn for this pur- 
pose, forms an important branch of trade in China. 
