Within recent years a number of new compounds of silver have been placed on the market. These have been devised to obviate, in part, the irritating effects of silver nitrate, as well as to avoid the limited action of this drug because of its property of coagulating proteids. Further, in internal therapy, since chlorides form insoluble compounds, these newer bodies have been made to avoid this chemical change. Among the more important of these may be mentioned: Argentol, argonin, argentamin, protargol, largin, actol, itrol, ichthyargon, and colloidal silver (collargolum).

Argentol. - This is a synthetic compound of quinaseptol and silver, which breaks up into oxychinolin and metallic silver. It is non-caustic, and is valuable in surgical wounds, skin affections, and has been employed in gonorrhea, but is not so valuable as protargol for this disease.

Argonin. - Origin. - A soluble compound of silver and casein, first prepared by Rohmann and Liebreich.

Description and Properties. - A dilute solution of this substance in water is opalescent; opaque when concentrated, but immediately cleared by the addition of ammonia or carbonate of soda. Used externally and locally.

Argentamine. - In order that a deeper action of silver might result, this solution of silver phosphate in aqueous solution of ethylendiamine was prepared. It was found, however, that the amine was too irritating, and this preparation has but limited application.

Protargol. - This product is the result of the attempt to obtain a compound of silver with an organic substance, albumose, which should be soluble and unirritating, and yet have the strong bactericidal properties of the metallic silver. It is a yellow powder, readily soluble in water, and contains 8.3 per cent. of silver. The solution is not affected by heat, albumin, hydrochloric acid, sodium chloride, or caustic soda. It is but slightly irritating, and has proved one of the best agents in the treatment of gonorrhea yet given to the profession. It is employed in from 2 to 10 per cent. solutions, depending upon the irritability of the affected parts and the stage of the disease.

Largin. - This is a compound of much the same character as protargol, being silver combined with protalbin (Danilewsky), a paranuclein proteid prepared by Lilienfeld. This proteid combination is a gray powder, soluble in 9 parts of water, containing II. 1 per cent. of silver, and is not precipitated by chlorides nor by albumin. It is used in much the same manner as protargol. It is used in 1/2 to 2 per cent. solutions.

Actol. - This is lactate of silver, a white powder, odorless, tasteless, and soluble in 20 parts of water. It has been recommended as an antiseptic, and fulfils much the same indications that silver nitrate does.

Itrol. - This is similar to actol, being the citrate of silver. It is much less soluble in water - 1-4000. It has no advantages over the nitrate.

Ichthyargon is a combination of silver and ichthyol. Its position in therapy is not yet established.

Colloidal Silver (Collargolum). - Finely divided metallic silver was introduced by Crede as an antiseptic in 1898. By the process of trituration metallic silver is converted into a soluble form, making, with water, a brownish solution. In this form it is used in internal hypodermic medication - 1/2-1 per cent. (10-30 m.) - or the colloid silver is made up as an ointment.

The ointment should be rubbed into a part for from twenty to thirty minutes, and has been highly praised for the treatment of lymphangitis, adenitis, boils, septicemia, erysipelas, puerperal fever, or other septic process, local or general. Failure to obtain results is said by its supporters to be due to insufficient rubbing.

Much more extended observation is desirable before trustworthy conclusions may be drawn concerning the value of colloidal silver. It is desirable that the ointment be freshly made.