428 POISONS I THEIR EFFECTS AND DETECTION. [§ 518 . 
to those which have been artificially prepared, such as methyl strychnine 
and methyl brucine, both of which have a curare-like action. And 
methoxyl groups have been found in tubo-curarine and curine. 
The mixed alkaloids of curare were first separated by Preyer in a 
crystalline form in 1865. He extracted curare with boiling alcohol, to 
which a few drops of soda solution had been added, evaporated off the 
alcohol, took up the extract with water, and, after filtration, precipitated 
by phosphomolybdic acid, which had been acidified with nitric acid. The 
precipitate was dried up with baryta water, exhausted with boiling 
alcohol, and the alkaloids precipitated from the alcoholic solution by 
anhydrous ether. It may also be obtained by precipitating with 
mercuric chloride solution, and throwing out the mercury afterwards 
by means of hydric sulphide, etc. 
The alkaloids so isolated form colourless, four-sided, very hygroscopic 
prisms of bitter taste, and weakly alkaline reaction ; soluble in water 
and alcohol in all proportions, but with difficulty soluble in amyl alcohol 
and chloroform, and not at all in anhydrous ether, bisulphide of carbon, 
or benzene. The bases form crystallisable salts with hydrochloric, 
nitric, and acetic acids. The alkaloids strike a purple colour with strong 
nitric acid. Concentrated solutions mixed with dilute glycerin give an 
amorphous precipitate with potassic bichromate, and the precipitate 
treated with sulphuric acid strikes a beautiful blue colour. The chromate 
is distinguished from strychnine chromate by its amorphous character, 
and by its comparatively easy solubility. If the chromates of strychnine 
and curare alkaloids be mixed, and the mixed chromates be treated with 
ammonia, strychnine will be precipitated and curare alkaloids pass into 
solution, thus forming a ready method of separating them. 
§ 518. Physiological Effects. —According to Voisin and Liouville’s 
experiments, subcutaneous injections of curare on man cause, in small 
doses, strong irritation at the place of application, swelling, and pain. 
The temperature of the body is raised from 1° to 2°, and the number of 
respirations increased from 4 to 8 per minute. The pulse becomes 
somewhat stronger and more powerful. The urine is increased, and 
contains sugar. Large doses administered to warm-blooded animals 
cause, after a short time, complete paralysis of voluntary motion and of 
reflex excitability, and the animal dies in asphyxia, the heart continuing 
to beat. 
This state is best produced, for the purpose of experiment, on frogs, 
and, indeed, is the best test for the poison. A very minute dose in¬ 
jected beneath the skin of a frog soon paralyses both the voluntary 
and respiratory muscles ; the animal continues to breathe by the skin ; 
the heart beats normally, or, perhaps, a little weakly, and the frog may 
remain in this motionless condition for days and yet recover. Onlv 
curare and its congeners have this effect. By tying the femoral artery 
