MORDANTS.

295

contains a certain amount of phosphate of soda and of carbonate of ammonia,which probably play an essential part. The use of cow-dung is apparently ofold origin, although on this subjedt no very precise data exist. It is knownthat the Swiss calico-printers and dyers made use of it in the middle of theeighteenth century, and M. J. Hausmann pointed out the benefits derivedfrom this material in 1790.* M. D. Kcechlin has set forth the favourableeffedts of the dunging in the following paragraphsf :—The aim to be attainedby the use of cow-dung is (1), to effect the entire combination of the sub-saltsof alumina with the fibre of the cloth, by causing the separation of nearly allthe acetic acid which had not been volatilised during the drying of themordant; (2), to dissolve and remove from the cloth a portion of the sub-stances which had been used as thickeners ; (3), to separate and remove fromthe fabric the uncombined portion of the mordant, and likewise to removesuch particles thereof as are simply mechanically fixed by the thickeners;(4), to prevent, by the peculiar nature of the substances which constitute thedung, the fixing upon the white portions of the cloth of any non-combinedmordant which becomes soluble by the acetic acid set free, and which acid atlast accumulates in the dung-bath. As for the theory of the action of the dung,the clue must be sought in its composition. The labours of Morin,J Perrot,§and Camille Kcechlin have elucidated this question to a certain degree, with-out, however, solving the question completely. According to M. Morin, thefiltered aqueous extradt of cow-dung, after having been exhausted by alcoholand ether, yields to water a soluble principle which he has named bubuline,and which he considers to be the adtive constituent, because, according to hisexperiments, this material has the property of precipitating most of the solu-tions of metals : later researches have shown, however, that the bubuline hasno separate existence as an immediate principle, being rather a mixture ofalbumenoid materials, coloured by compounds due to the bile, and of vegetableorigin. According to M. Perrot, cow-dung from animals fed with dry fodder,

contains in 100 parts—

Water .69*58

Bitter principle . 0*75

Saccharine matter . 0*93

Chlorophyll. 0*28

Albumen .. 0*63

Lignine.26*99

Chloride of sodium . 0*08

Sulphate of potassa ... 0*05

Sulphate of lime. 0*25

Carbonate of lime . 0*24

Phosphate of lime . 0*46

Carbonate of iron .. .. .. .. 0*09

Silica . 0*14

100*47

* Lettre a Berthollet, “ Annales de Chimievol. xii., p. in.

t “ Bulletin de la Society Industrielle,” vol. i., p. 313. At the time this was written theageing process, at least as now known and practised, was not used,t “ Bulletin de la Societe Industrielle," vol. iv., p. 164.

§ Ibid., vol. viii., pp. 113 and 124.