[268] Mercury cyanide may be detected in a liquid after acidifying with tartaric acid, and adding a few c.c. of SH₂ water and then distilling. S. Lopes suggests another process: the liquid is acidified with tartaric acid, ammonium chloride added in excess, and the liquid is distilled. A double chloride of ammonium and mercury is formed, and HCN distils over with the steam.--_J. Pharm._, xxvii. 550-553. =Silver cyanide= acts, according to the experiments of Nunneley, also like hydric cyanide, but very much weaker. =Hydric sulphocyanide= in very large doses is poisonous. =Potassic sulphocyanide=, according to Dubreuil and Legros,[269] if subcutaneously injected, causes first local paralysis of the muscles, and later, convulsions. [269] _Compt. rend._, t. 64, 1867, p. 561. =Cyanogen chloride= (CNCl) and also the compound (C₃N₃Cl₃)--the one a liquid, boiling at 15°, the other a solid, which may be obtained in crystals--are both poisonous, acting like hydric cyanide. =Methyl cyanide= is a liquid obtained by distillation of a mixture of calcic methyl sulphate and potassic cyanide. It boils at 77°, and is intensely poisonous. Eulenberg[270] has made with this substance several experiments on pigeons. An example of one will suffice:--A young pigeon was placed under a glass shade, into which methyl cyanide vapour, developed from calcic methyl sulphate and potassic cyanide, was admitted. The pigeon immediately became restless, and the fæces were expelled. In forty seconds it was slightly convulsed, and was removed after a few minutes’ exposure. The pupils were then observed not to be dilated, but the respiration had ceased; the legs were feebly twitching; the heart still beat, but irregularly; a turbid white fluid dropped out of the beak, and after six minutes life was extinct. [270] _Gewerbe Hygiene_, p. 392. The pathological appearances were as follows:--In the beak much watery fluid; the membranes covering the brain weakly injected; the _plexus venosus spinalis_ strongly injected; in the region of the cervical vertebra a small extravasation between the dura mater and the bone; the right lung of a clear cherry-red colour, and the left lung partly of the same colour, the parenchyma presented the same hue as the surface; on section of the lungs a whitish froth exuded from the cut surface. In the cellular tissue of the trachea, there were extravasations 5 mm. in diameter; the mucous membrane of the air-passages was pale; the right ventricle and the left auricle of the heart were filled with coagulated and fluid dark red blood; liver and kidneys normal; the blood dark red and very fluid, becoming bright cherry-red on exposure to the air; blood corpuscles unchanged. Cyanogen was separated, and identified from the lungs and the liver.