568 Chronicles of Science. [ Oct., 
that of sweet almonds remained uncoloured by rosaniline; poppy 
oil became slightly red; linseed oil became strongly coloured, its 
natural colour rendering the tint brownish; palm-oil gave a colora- 
tion still more intense. It is sufficient to mix olive oil with 5 per 
cent. of oleic acid to obtain with rosaniline a tint equal to that of 
raspberry juice. 
Mr. E. Smith has given the following very simple test for the 
presence of a free acid :—Dissolve chloride of silver in just sufficient 
ammonia to make a clear solution. If a little of the test be added 
to ordinary spring water, the carbonic acid present in the latter will 
neutralize the ammonia and precipitate the chloride. This forms a 
good lecture experiment, the test being a very delicate one. 
We hear that a new source of thallium has been discovered in 
the flue dust obtained from a sulphuric acid works in Holland, where 
pyzites from Suhrort is burned. ‘This flue dust contains about 1 
per cent. of thallium. 
Drs. Crum Brown and T. R. Fraser have made an interesting 
discovery upon the influence of direct chemical addition upon the 
physiological action of substances. The bodies which they have 
chosen for examination are the more active of the vegetable alka- 
loids, and the chemical operation of which they have studied the 
effect has been the direct addition of iodide of methyl. It was 
shown by How, that when iodide of methyl acts upon strychnine, 
brucine, morphia, and other alkaloids, it adds itself to them, and 
beautiful crystalline bodies are produced, which differ considerably 
in character from the salts of the alkaloids. The authors have 
already examined the physiological action of the bodies produced by 
the addition of iodide of methyl to strychnine, brucine, morphia, 
thebaia, codein, and nicotine. 
It is well known that doses of strychnine, varying from one- 
twentieth to one-thirtieth of a grain, rapidly produce in rabbits most 
violent convulsions, and in a few minutes kill the animal; the phe- 
nomena produced being due to a localization of its action on the 
cord. It was found that twelve grains of iodide of methyl-strych- 
nine, when administered (by subcutaneous injection) to rabbits 
weighing three pounds, produced no effect whatever. Fifteen grains 
produced symptoms, and twenty killed; but the animal died with 
symptoms altogether different from those produced by strychnine. 
In place of violent and spasmodic convulsions and muscular rigidity, 
the appearances were those of paralysis with complete general flac- 
cidity. ‘The spinal motor nerves were either paralysed or speedily 
became so; and, instead of the speedy occurrence of muscular rigid- 
ity, the muscles remained flaccid, contractile, and alkaline for several 
hours. In short, by the addition of methyl to strychnine the toxic 
properties of the latter are diminished about 140 times; and the 
