398 
NICOTIN A, AND ITS EFFECTS ON ANIMALS. 
water by simple exposure. The hydrochlorate of ammonia 
forms permanent dagger crystals; the hydrochlorate of nico- 
tina is deliquescent, or only imperfectly crystallizes in short 
wide prisms crossing each other at right angles. 
“ Nicotina strikingly resembles ammonia in some of its pro¬ 
perties, and as ammonia may result from the action of potash 
on organic matter, especially when heat is employed, it is 
necessary that an analyst should have the means of distin¬ 
guishing nicotina from ammonia, and of separating one from 
the other. They both produce an orange-yellow precipitate 
with chloride of platina : when examined by the microscope 
the ammonia-precipitate is in octahedra or dodecahedra—the 
nicotina-precipitate is seen in groups of feathered crystals 
peculiar in shape and arrangement, mixed with well-defined 
octahedra. Both ammonia and nicotina are precipitated of a 
yellow colour, by arsenio-nitrate of silver, and white bv corro- 
sive sublimate. The striking chemical reactions in which 
they differ are these: iodine water has its colour discharged 
by ammonia; it is precipitated brown by nicotina: tannic 
acid produces a red colourwith ammonia, without precipitating 
the alkali; it precipitates nicotina of a pale yellowish white, 
like the other alkaloids, but produces no change of colour ; 
traces of ammonia are thus easily detected in a solution of 
nicotina by this reagent. Gallic acid rapidly imparts to am¬ 
monia a pink-red colour, while it produces no change of colour 
or precipitate in nicotina. The red colour produced by am¬ 
monia slowly changes to an olive green. Chloride of gold 
gives an amorphous brown precipitate of fulminating gold 
with ammonia, while it produces a plumose crystalline pre¬ 
cipitate of a yellow colour in a solution of nicotina. Nitrate 
of silver yields with ammonia brown oxide of silver, soluble 
in an excess of the alkali; with nicotina it produces an opa¬ 
lescence not soluble in excess ; and, on heating the mixture, 
silver is slowly reduced and separated. Permanganate of 
potash is scarcely affected in its colour by admixture with 
ammonia; but the colour is rapidly destroyed by nicotina 
even in a very diluted state. As ether and most organic 
substances discharge the pink colour of the permanganate, 
care must be taken that the nicotina is not combined with 
any of these matters. When we know that we are dealing 
with nicotina alone, a standard solution of permanganate of 
potash may be employed to determine the quantity present. 
The quantity of permanganate which has its colour discharged 
on admixture with a certain measure of nicotina, will be great 
in proportion to the strength of the alkaloid ; and if the 
solution of permanganate be previously tested with a mea- 
