M. TECHNOLOGY. 489 



it in from one to one and a half hours. The Gramme ma- 

 chhie is suggested for the production of ozone. 24 (7, XV., 

 113. 



WATER-PROOFING FABRICS WITH BICHROMATED GELATIN. 



In cases where a certain degree of stiffness -is not objec- 

 tionable, as in the manufacture of canvas trunks, knapsacks, 

 etc., and possibly also of roofing-paper, the material may be 

 easily and cheaply rendered water-proof by simply stretch- 

 ing it in a frame, and coating it several times -with a hot five 

 to ten per cent, solution of gelatin, to which one part of bi- 

 chromate of potash has been added in solution for every five 

 of gelatin, and then exposing it to sunlight, or diffused day- 

 light. 13 C, December 15, 1875, 1560. 



DYEING PARCHMENT PAPER WITH ANILINE COLORS. 



So-called vegetable parchment can, like silk and wool, be 

 combined directly with aniline dye-stuffs without a mor- 

 dant, and in this way a very durable material, of a variety 

 of colors, may be prepared, suitable for book-bindings, fancy 

 boxes, cases, etc. 5 (7, XXXIL, 1875, 256. 



DISCHARGING ANILINE BLACK FROil FABRICS. 



In order to discharge black from fabrics dyed with ani- 

 line black, Witz treats the portion with an acidified solution 

 of permanganate of potash, w^hereby peroxide of manganese 

 is precipitated in the fibres. A solution of oxalic acid is then 

 used, which removes the peroxide, and leaves the parts of the 

 cloth acted on perfectly white. It is suggested that a solu- 

 tion of the permanganate, thickened with infusorial earth, 

 could be printed on fabrics, and thus discharge white figures 

 on an aniline-black ground. 6 C, January 21, 1875,29. 



ARTIFICIAL ULTRAMARINE INDUSTRY. 



The total production of artificial nltramarine during the 

 year 1874 was 150,000 cwt., of the value of 13,000,000. The 

 manufacture is chiefly confined to Germany and France, the 

 former country exporting annually about 60,000 cwt. In 

 addition to the greenish -blue, pure blue, and violet -blue 

 shades, a violet ultramarine was among the exhibits of the 

 Vienna Exposition. The composition and mode of prepara- 



X 2 



