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ELEMENTS OF MATERIA MEDICA.

malignant scarlatina, and ulcerated sore throat. It is usually adminis-tered, in these cases, in conjunction with the vegetable tonics; as cin-chona or quassia. We frequently employ it to counteract phosphaticdeposits in the urine. After a copious evacuation, it is, according to Dr.Paris, the most efficacious remedy for preventing the generation ofworms ; for which purpose the infusion of quassia, stronger than that ofthe Pharmacopoeia , is the best vehicle. It has been employed with bene-fit in some forms of dyspepsia. Two facts give a remarkable interest tothe employment of this acid in dyspeptic complaints; namely, that it isa constituent of the healthy gastric juice ; and, secondly, when mixedwith mucus, it has a solvent or digestive power in the case of variousarticles of food, as before mentioned. Lastly, hydrochloric acid hasbeen used in scrofulous and venereal affections, in hepatic disorders, &c.

(i b .) External. —In the concentrated form it is employed as a caustic todestroy warts, and as an application in sloughing phagedaena, though forthe latter purpose it is inferior to nitric acid- Properly diluted it formsa serviceable gargle in ulceration of the mouth and throat. The objec-tion to its use as a gargle is its powerful action on the teeth: to obviatethis as much as possible, the mouth is to be carefully rinsed each timeafter using the gargle. It is sometimes applied to ulcers of the throatby means of a sponge. Water acidulated with this acid has beenapplied to frostbitten parts, to chilblains, &c. An injection composedof from 8 to 12 drops of the acid to three or four ounces of water, hasbeen employed as an injection in gonorrhoea.

Administration. —It is given, properly diluted, in doses of from five tofifteen or twenty minims. The diluted acid of the Pharmacopoeia maybe administered in doses of from half a fluidrachm to one fluidrachm.The most agreeable mode of exhibiting it is in the infusion of roses,using the hydrochloric instead of sulphuric acid.

Antidotes. —In a case of poisoning by this acid, the antidotes arechalk, whiting, magnesia or its carbonate, and soap; and in the absence ofthese, oil, the bicarbonated alkalies, milk, white of egg, or demulcents ofany kind. Of course the gastro-enteritis is to be combated in theusual way.

Order 6.—Nitrogen, and its Compounds withOxygen andHydrogen.

Nitroge'mum. — Nitrogen.

History and Synonymf.s. —This gas was first recognised by Dr.llutherford, in 1772. He termed it mephitic air. Priestley called itphlogisticated air. Lavoisier , a'zote ( azo'tum). Cavendish, finding it tobe a constituent of nitric acid, gave it the name it now usually bears(nitrogen).

Natural History.— It is found in both kingdoms of nature.

(a.) In the inorganized kingdom. —It has not hitherto been found innon-fossiliferous rocks. It is a constituent of coal, of nitrates, of ammo-niacal salts, and of some mineral waters. It forms 79 or 80 per cent, ofthe atmosphere.

(A) In the organized kingdom. —It is a constituent of various vegetableprinciples, as the organic alkalies, gluten, and indigo blue ; and is par-ticularly abundant in the families Crucifer a. and Fungi. It enters intothe composition of most animal substances, as albumen, fibrin, gelatine,