One-third by weight of salvarsan is arsenic, and therefore in administering 0.6 gm., which is an ordinary dose, we are giving the patient 0.2 gm. of arsenic, or fifty times the amount that in the usual pharmaceutic combinations would cause poisoning. It is through the genius of Ehrlich that a way has been found to give this enormous dose, and almost always without causing any disagreeable symptoms, with the exception of pain— and even pain may be eliminated by injecting the drug intravenously. That great care must be observed in giving it goes without saying.
The drug is put up as a dry powder, enclosed in glass tubes, and in this form is stable; at least I have never yet heard of any trouble arising from its decomposition in the tubes. In solution, however, it quickly decomposes; in simple water it forms an acid solution that lasts undecomposed for several