popularly
known as salvarsan or "606." Other preparations, such as kharsivan,
arseno-billon, and diarsenol, are chemically equivalent to salvarsan,
containing from 27 to 31 per cent. of arsenic, and are equally
efficient. The full dose is 0.6 grm. All these members of the "606"
group form an acid solution when dissolved in water, and must be
rendered alkaline before being injected. As subcutaneous and
intra-muscular injections cause considerable pain, and may cause
sloughing of the tissues, "606" preparations must be injected
intravenously. Ehrlich has devised a preparation--neo-salvarsan, or
"914," which is more easily prepared and forms a neutral solution. It
contains from 18 to 20 per cent. of arsenic. Neo-kharsivan,
novo-arseno-billon, and neo-diarsenol belong to the "914" group, the
full dosage of which is 0.9 grm. As subcutaneous and intra-muscular
injections of the "914" group are not painful, and even more efficient
than intravenous injections, the administration is simpler.

Galyl, luargol, and other preparations act in the same way as the "606"
and "914" groups.

The "606" preparations may be introduced into the veins by injection or
by means of an apparatus which allows the solution to flow in by
gravity. The left median basilic vein is selected, and a platino-iridium
needle with a short point and a bore larger than that of the ordinary
hypodermic syringe is used. The needle is passed for a few millimetres
along the vein, and the solution is then slowly introduced; before
withdrawing the needle some saline is run in to diminish the risk of
thrombosis.

The "914" preparations may be injected either into the subcutaneous
tissue of the buttock or into the substance of the gluteus muscle. The
part is then massaged for a few minutes, and the massage is repeated
daily for a few days.

No hard-and-fast rules can be laid down as to what constitutes a
complete course of treatment. Harrison recommends as a _minimum_ course
of one of the "914" preparations in _early primary cases_ an initial
dose of 0.45 grm. given intra-muscularly or into the deep subcutaneous
tissue; the same dose a week later; 0.6 grm. the following week; then
miss a week and give 9.6 grms. on two successive weeks; then miss two
weeks and give 0.6 grm. on two more successive weeks.

When a _positive Wassermann reaction_ is present before treatment is
commenced, the above course is prolonged as follows: for three weeks is
given a course of pot