70 DR ANDERSON ON CODEINE, AND 
added ; if no precipitate appears, the heat is kept up for a short time longer, and 
another quantity is then taken out and tested; and this is repeated ‘until the 
precipitate, which makes its appearance when the acid:is neutralised, ceases to 
increase. The fluid is then immediately saturated with ammonia, and stirred ra- 
pidly, when it becomes filled with a bulky precipitate of nitrocodeine. The action 
which takes place is extremely rapid, and the whole operation is complete in a 
few minutes; so that the experimenter requires to be carefully on the watch, in 
order to hit the right moment for precipitating the fluid. No red fumes are 
evolved; if they are seen, it is a sure sign that the action has gone too far, and 
that part of the codeine has been converted into the resinous acid already men- 
tioned. On this account it is better to stop the action before the whole of the | 
codeine is decomposed, the quantity left being easily recovered from the solu- 
tion; but even with the greatest possible care, the formation of a small quantity 
of the resinous acid cannot be avoided, and its presence is always indicated by 
the dark colour which the fluid acquires when saturated by ammonia. 
On the addition of ammonia, the nitrocodeine falls in the form of minute 
silvery plates, with a very slight shade of yellow. It is purified by solution in 
hydrochloric acid, boiling with animal charcoal and a reprecipitation with ammo- 
nia, in order to separate colouring matter and any unchanged codeine which may 
have been precipitated along with the first crystals. The nitrocodeine is then 
crystallised by dissolving in dilute alcohol, or a mixture of alcohol and ether. 
Nitrocodeine crystallised from alcohol is deposited in the form of slender 
silky needles of a pale fawn-colour, which, on drying, mat together into a silky 
mass. From alcohol and ether it is obtained by spontaneous evaporation in small 
yellowish crystals, which, under the microscope, are seen to be four-sided prisms, 
terminated by dihedral summits. Nitrocodeine is sparingly soluble in boiling 
water, from which it is deposited in minute crystals on cooling. It dissolves 
abundantly in boiling alcohol, and but sparingly in ether. It is soluble in acids, 
with the formation of salts which are neutral to test-paper, and from which pot- 
ash and ammonia precipitate the base as a crystalline powder. When heated 
carefully, it melts into a yellow fluid, which concretes on cooling into a highly- 
crystalline mass. At a higher temperature, it suddenly decomposes without 
flame, leaving a bulky charcoal. 
Its analysis yielded the following results, of which No. 1 is from the base 
crystallised from the first precipitate by ammonia, before I had observed its ten- 
dency to carry down codeine with it, and which has therefore given a slight ex- 
cess; the others are from the pure base. Crystallised nitrocodeine is anhydrous. 
5748 am of nitrocodeine, dried at 212°, gave 
1 13:301 of carbonic acid, and 
" Out2Z8) 2... of water. 
9°523  ... of nitrocodeine gave 
II 12-724 ... of carbonic acid, and 
2°887 ~... water, 
