of the most common impurities found in carbolic aoid is coal-tar oil. This can eaaily be detc,cted by mixing the suspected acid with a solution of pure caustic soda, 14° Tw. at 15° (60° F.), one volume of the former to two of the latter, and agitating. If pure, the solution Will be complete ; tho amount left undissolved after settling will indicate the proportion of im purity. Pure carbolic acid gives a blue colour to pine wood previously treated with hydrochloric aoid : a green colour indicates aniline ; and a brown, pyrrhol.
Poisonim and Antidotes.—In cases of poisoning with oarhelits acid, Dr. Calvert recommends the administration of copious doses of castor and sweet oils. In cases of external burns, glycerine should be immediately applied, and the affected parts ahould be repeatedly washed with it. Dr. 3. Rase mann recommends a strong solution of saccharate of lime, as an antidote. Carbolic aoid is a most powerful poison ; it can cause death even *hen it acts only upon the akin, and it should never be sprinkled upon floors, nor upon any surface likely to be used as a seat, unlese it be in perfect solution in water. In an impure state, or in eolution, it bas been swallowed in mistake for porter or spirits. The signs indicating poisoning by carbolic acid are eapecially the whitenesa of the mouth, tongue, and fames, and the characteriatic odour. Dr. Saneom recommenda the immediate administration of the white of eggs.
Tests.—Besides the teats already indicated on p. 41, attention is directed to the following (1) Dr. W. F. Koppeschecar'a method of eetimating volumetrically, by the aid of a titrated volume of hydrobromic acid, fully detailed by him in the ' Moniteur Scientifique,' April, 1878. (2) Prof. E. W. Davy observes that a aolution of molybdic acid in eulphuric acid produces a light-yellow or yellowish-brown tint, developing into purple. This test appears not to be interfered with by the presenco of organic substances, and affords a means of distinguishing creaeote from carbolic acid, a matter of commercial importance, much of what is sold as creasote being little else than carbolic) acid. Recent files of the Analyst ' may also be consulted with advantage.
Uses.—The next consideration will be eome of the uses which may be made of carbolic or phenio aoid (oi rather alcohol, for its properties are alcoholic rather than acid), for sanitary, domestic, agri cultural, and manufacturing purposes.
The antiseptic or germ-killing properties of this substance are very remarkable. Research and
discovery have shown that all fermentation and putrefaction are due to the presence of microscopic animals or vegetables, which, during their vitality, decompose or change organic substances, so as to produce the effects which are witnessed. As carbolic acid exercises a most powerful destructive action upon these microscopic and primitive sourcee of life, it ia therefore an antiseptio and disin fectant, much more active and much more rational than thoee generally in use.
It is necessary here to make a few remarks, explanatory of the distinctions between deodorizers, disinfectants, and antiseptics. All substances acting merely ste deodorizers are neither disinfectant° nor antiseptice, as they aimply remove the noxious gases and odoura emitted from organic matters whilet in a state of decay or putrefaction, without having the property of arreating decomposition or fermentation. It has been proved that the aource of infection does not lie in the noxious gases and bad smells (which are simply indicatora of its probable exiatence), but in microscopic spores floating in the atniosphere, and which are ultimately developed and propagated.
Disinfectants are those bodies which prevent the spread of infection. Under thie head, may be classed bleaching powder or chloride of lime, sulphurous acid, and permanganate of potash. They act firat as deodorizere, and then ae disinfectants ; but they muat be employed in large quantities to thoroughly oxidize or burn up organic mattere, so as to prevent them from again entering into decompoeition when exposed to the atmosphere. They are, in fact, rather destructive agents than disinfectanta properly so called, and are never antiseptics.
Antiseptics, auch as corrosive sublimate, araenious acid, essential oile, carbolic acid, Stc., act as such by destroying all source of decay and decomposition, that is to say, they destroy or prevent the formation of the germs of putrefaction and fermentation, without acting upon the animal or vegetable matters present. The advantage of their use ie, therefore, that they act, when used in amall quantitiee, upon tho primary source of a atate of decay in all organic matter& Further, they are deodorizers, inasmuch as they arrest the progrees of that decomposition which gencratee offensive odours ; thus, while an antiseptic is, of necessity, at the same moment, a deodorizer and a disinfectant, these latter are not necessarily, and probably never are, antiseptic.