Dr Maclagan[144] states that he found when administered in doses of 10 gr. to 1⁄2 dr., every 2 to 4 hours, the pain and fever ceased in the course of 48 hours. The results are stated to have been quite as favorable as those following the employment of salicylic acid. It was found to effect with certainty a great reduction in the bodily temperature.
[144] ‘Lancet,’ March 4th and 11th, 1876.
Pur. & Tests.—1. It is entirely soluble in water and rectified spirit.—2. When strongly heated it is wholly dissipated, and, if kindled, burns with a bright flame, leaving a bulky charcoal.—3. Its solution is absolutely neutral to test-paper.—4. Concentrated sulphuric acid causes it to agglutinate into resin-like lumps, with the accession of an intense blood-red colour.—5. When its aqueous solution is mixed with some hydrochloric acid, or dilute sulphuric acid, and the mixture is boiled for a short time, the liquid suddenly becomes turbid, and deposits SALIRETIN, under the form of a granular crystalline precipitate. This is characteristic.—6. No reagent deposits salicin without decomposition. See Salicylic and Salicylous acids.
SAL′ICYL. C7H4O. A compound radical, forming the basis of the so-called SALICYL-COMPOUNDS, or SALICYL-SERIES. It is known only in combination. The volatile oil of meadow-sweet is a natural hydride of salicyl, a substance which, when artificially prepared, is better known under the name of SALICYLOUS ACID. (See below.)
SALICYL′IC ACID. H2C7H4O3. A peculiar volatile, crystallisable acid, discovered by Piria. It is obtained by fusing salicylous acid with solid hydrate of potassa in slight excess, until the mixture turns white and gas is disengaged, and treating a solution of the residuum with hydrochloric acid, in slight excess to separate the potassa; the salicylic acid separates in crystals, which are purified by solution in hot water. It may also be obtained from the oil
of partridge-berry (Gaultheria procumbens), by acting on it with a strong and hot solution of potassa, and afterwards separating the acid as before. This oil is methylo-salicylic ether, or salicylate of methyl. In its general properties, salicylic acid closely resembles benzoic acid.
The greater part, if not the whole, of the salicylic acid of commerce is now obtained by a method invented by Professor Kolbe. This process, which consists in acting on sodium carbolate with carbonic acid, is thus described in the ‘Archiv der Pharm.,’ 3rd series, v, 445.[145] In a strong crude soda liquor of known strength is dissolved a sufficiency of previously melted crystals of carbolic acid to saturate the soda.
[145] ‘Pharm. Journal,’ 3rd series, v, 421.
The solution is then evaporated in an iron capsule, and by means of stirring brought to a dry powder. The sodium carbolate so obtained is gradually heated in a retort to a temperature of from 220° to 250° C., in a continuous current of dry carbonic anhydride.
The reaction is ended when at the above-mentioned temperature no more carbolic acid passes over. It might have been expected that, the reaction going forward in this manner, a molecule of carbonic anhydride would have been introduced into the molecule of sodium carbonate, and thus a molecule of sodium salicylate be formed.