450 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



a half of alcohol of ninety per cent. Rinsing, drying, press- 

 ing, and, when found suitable, sizing with a little glue, finish 

 the process. 25 (7, xix., 153. 



BARYTES WHITE. 



Mr. Pfundheller informs us that the most beautiful white 

 known to dyers may be obtained by the following method : 

 For each hundred pounds of w T ool, three pounds of alum, one 

 pound of cream of tartar, and tw T o pounds of sulphuric acid 

 are to be combined with one eighth of an ounce of soluble 

 iodine violet, and the wool immersed in the solution at a tem- 

 perature of 122 Fahr., and stirred round for an hour at this 

 temperature. Another bath is to be made in the mean time, 

 in a fresh kettle, with three pounds of chloride of barium, and 

 the whole immersed in this, and kept at a temperature of 122 

 Fahr. for two hours. By this process the sulphate of barytes, 

 the most beautiful of whites, will be thrown down in the fibre 

 of the w^ool, which has been saturated in the first bath w T ith 

 the sulphuric acid, and it w T ill gain about eighteen per cent, 

 in weight. 23 (7, xiii., 180. 



SUBSTANCES FOR SIZING FABRICS. 



In printing designs upon fabrics it is necessary to impart 

 to the coloring matter a certain degree of consistency, in or- 

 der that it shall occupy a particular space with sharply de- 

 fined edges. Vegetable substances are specially adapted to 

 this purpose, the principal consisting of starch, gum arabic, 

 gum Senegal, gum tragacanth, sugar, sirup, dextrine, etc. As 

 some of these have a special chemical or mechanical reaction 

 w r hen used in connection with particular coloring matters, it 

 becomes necessary to exercise a careful discrimination in 

 their employment ; and it is highly important that they be 

 readily removable, after they have served the purpose of 

 their application, by subsequent washing. Among the most 

 generally applicable of all, however, are the substances usu- 

 ally known as leicom and dextrine, both prepared from starch, 

 the former by the action of heat, and the latter by means of 

 an acid. These are supplied in the form of powder, either 

 white or dark colored, or as granular masses, and sometimes 

 as solutions resembling a thick yellow sirup. For the prepa- 

 ration of the leicom (or leiacom, as it is sometimes called) 



