CARBOLIC ACID. 355 



added to their nutritive medium, likewise if pot plants be watered with 

 a solution of O'S per cent strength. A solution of 1 per cent is per- 

 nicious to cherry-tree and peach-tree leaves. Used to disinfect corn- 

 seed it does not lower the germinative capacity. 



Action on Fungi. — As determined by Bull it requires a 5 per cent 

 solution of carbolic acid to coagulate the white of egg, gelatine, and 

 casein ; the precipitate is not a chemical derivative but a dehydrated 

 albumen, the carbolic acid being capable of being removed by v^ashing. 

 The action of carbolic acid on the spores of iungi ought, therefore, 

 to be less energetic and more uncertain than that of copper salts which 

 yield with albumens stable insoluble compounds. The effect of 

 carbolic acid on saprophytic fungi such as Penicillium glaiiciim has 

 been studied by Plugge. A solution of 1-1-5 per cent kills them. 

 According to Neumann a 0-1 per cent solution in no way hinders the 

 germination of their spores, a 0"2 per cent solution retards this ger- 

 mination, and a 0-3 percent solution acting several times on the spores 

 ends up by kilUng them. Lemaire prevents the moist mould of flour 

 by a 5 per cent solution. Ferments are affected as follows by carbolic 

 acid : A solution of 1-2 per cent strength interferes with the fermenta- 

 tion. A solution of 5 per cent strength prevents it. The action on 

 bacteria is pronounced. Bucholz has shown that if a solution of 

 0-5 per cent strength interferes with their development, a 4 per cent 

 solution prevents their multiplication. 



Action on Insects. — Carbolic acid is poisonous to insects; its 

 property of coagulating albumen puts it on the same plane as metallic 

 salts endowed with the same property, e.g. salts of copper, silver, and 

 mercury, but this action is weak. As Bull has shown, a solution of 

 5 per cent strength coagulates white of egg, a 3 per cent solution only 

 renders it turbid, and a 1 per cent solution leaves it limpid. Gelatine 

 and casein behave in the same way. According to Perroncito, the 

 eggs of Bombyx Mori, L., still hatch after steeping two hours in a 1 

 per cent solution of carbolic acid. 



Use. — Carbolic acid has found several uses. It is used in aqueous 

 solution, in soapy emulsions, in admixture with silicate of soda, in 

 absorption by sawdust, by injection into the sap of plants, and in 

 spraying. 



Use as Weed Killer. — Pammel recommends a 25 per cent 

 emulsion of carbolic acid in water to destroy Cnicus arvensis (char- 

 lock of Canada). The plant is cut 8 inches underground and the 

 young shoots produced are washed afterwards with the emulsion. 



Phoma Bcke (disease of the leaves of the petiole of the beet). — 

 Carbolic acid plays the preponderant role in the disinfection of beet 

 seeds against bacterian and' cryptogamic diseases. Kruger asserts a 



1 per cent solution acts more surely than steeping for twenty hours 

 in a 0-4: per cent solution of blue vitriol ; for forty-eight hours in a 



2 per cent bouillie bordelaise ; for eight hours in a U"02 per cent mer- 

 curic chloride, and yet it does not lower the germinative capacity of 

 the seeds. The first experiments of 1890 made by Hellriegel consisted 

 in steeping for twenty hours in a 1 per cent solution of carbolic acid. 

 They yielded as a result of twenty experiments, 98 per cent of sound 



