METALS AND METALLOIDS 707 



Salvarsan inhibits the growth of trypanosomes in a test-tube as 

 well as in the body of the host. It contains the two contiguous 

 0^0-aminohydroxyl groups which serve as " haptophores " 

 for attaching the molecule to the parasitic organism. Ehrlich 

 compares the compound to the poisoned arrows used by 

 savages, the amino- phenol complex being the barbed arrow- 

 head, the two benzene nuclei serving as the shaft of the arrow, 

 while the two unsaturated arsenic atoms are the poison smeared 

 on the arrow. 



The drug is made up in the form of its dihydrochloride 

 (III.), and the practical difficulties attending its use are its 

 great oxidisability and the careful preparation needed to secure 

 a neutral solution, which is especially necessary when the 

 substance is administered intravenously. To obviate the latter 

 difficulty a modified drug has been devised, known as Neo- 

 salvarsan (IV.), which is prepared by treating salvarsan with 

 formaldehyde sulphoxylate, the result being that one or two 

 CH 2 . S0 2 H groups become attached to aminic nitrogen, so that 

 the product becomes distinctly acidic and capable of forming 

 a stable neutral sodium salt (IV.). 



Organic Derivatives of Antimony 



Antimony has long been administered therapeutically in the 

 form of its salts, especially as potassium antimonyl tartrate, 

 the well-known tartar emetic. It would be of great interest 

 to ascertain what modification in the action of the metalloid 

 would be effected by combining it with hydrocarbon radicals. 



Many organic derivatives of antimony are known containing 

 alkyl or aryl radicals, or both. I do intend discussing these 

 beyond showing the steps by which quite recently the antimony 

 analogue of atoxyl has been reached. We may expect the 

 antimony analogue of salvarsan to follow, although its advent 

 has not yet been recorded. 



The best general method of attaching aromatic radicals to 

 antimony is through the Grignard reaction, as, for example, 

 with antimony trichloride and magnesium phenyl bromide, 

 this condensation leading to triphenylstibine. From this product 

 three series of aromatic antimony compounds can be obtained 

 containing one, two, and three phenyl radicals attached to 

 antimony. By chlorination followed by hydrolysis the corre- 



