L. TECHNOLOGY. 479 



CHINESE WATER-PROOFING. 



According to Dr. Scherzer, the Chinese are in the habit of 

 making use of a composition called schioicao, which has the 

 property of rendering wood and other substances perfectly 

 water-tight. This is stated to be composed of three parts of 

 blood deprived of its fibrin, four of lime, and a little alum. 

 A card-board covered with this is said to become as hard as 

 wood, and it is constantly used in coating wooden buildings 

 in Pekin, so as to render them water-proof. 18 A, January 

 13,408. ' 



WATEE-PEOOFING CLOTHING. 



A method of rendering fabrics water-proof, either in the 

 piece or when made up into garments, without at the same 

 time impeding transpiration, and one lately recommended in 

 Paris for military purposes, consists in the use of an acetate 

 of alumina, prepared by the mutual decomposition of solutions 

 of acetate of lead and of sulphate of alumina. The fabrics 

 are dipped in this solution and then dried, in which process 

 acetic vapors are developed, and basic acetate of lead remains 

 behind, thus protecting the cloth completely against wet, 

 without being itself visible or appreciable in any other way. 

 The application will hold good for a long time if the portions 

 of the dress exposed are occasionally moistened with the so- 

 lution by means of a sponge. 6 (7, 1870, December 15, 502. 



COMPOSITION FOR WATEE-PEOOFING. 



Thirty grains of gum arabic are first dissolved in two hun- 

 dred and fifty grains of water. To this are added thirty 

 grains of the spirits of w T ine of commerce ; three hundred 

 grains of sulphate of alumina, of potash, or of soda are then 

 to be ground in a mortar to a fine powder, and to this is add- 

 ed, little by little, the gummy solution mentioned above. The 

 whole is kneaded together, and moulded into blocks or cakes 

 ready for use. To apply water-repellant compositions, such 

 as above described, to fabrics, to render them water-proof, 

 the composition is dissolved in water. If the solution is to 

 be used for treating woolen fabrics, the composition is dis- 

 solved in about one hundred and fifty times its weight in 

 water; if for cottons, in about one hundred times its weight ; 



