M. TECHNOLOGY. 539 



cemented place is much stronger than the material itself: 

 Form a thick paste with water-glass (silicate of soda) by- 

 adding as much as may be necessary of a mixture of 12 

 parts of Portland cement, 6 of slaked lime, 6 of fine sand, 

 and 1 of infusorial earth. The article to be cemented need 

 not be heated. It hardens in twenty-four hours. 18 (7, De- 

 cember 23, 1874, 815. 



CEMENT FOR MAEBLE WATER-TANKS. 



In the Berlin Polytechnic Society, water-glass with mar- 

 ble-dust, glycerine, and litharge was recommended as a ce- 

 ment for water-tanks of marble slabs, with the statement 

 that it was unaffected by hot water. A mixture of 12 parts 

 of cement, 6 of whitening, 6 of fine sand, and 1 of infusorial 

 earth, stirred to a paste with water-glass, was also mentioned 

 for the same purpose. 34 C, XXIII., 1874, 183. 



RENDERING IRON WIRE OF A SILVERY WHITENESS. 



To make iron wire of a silvery whiteness it is first treated 

 in a hydrochloric acid bath in which a piece of zinc is sus- 

 pended. The corroded wire is then brought in contact with 

 a plate of zinc in a bath in which 2 parts of tartaric acid 

 are dissolved in 100 parts of water, with further addition of 

 3 parts of tin salt (stannous chloride) and 3 parts of soda. 



The wire is allowed to remain some two hours in the bath, 

 and is made bright by polishing or by drawing in the draw- 

 ing-plate. By this galvanized tinning it is quite easy also to 

 whiten wire which is already rolled up spirally, or iron ob- 

 jects of any other form, which gives an advantage over the 

 mechanical method by which the wire is tinned at a high 

 temperature, and then passed through the drawing-plate. 

 21^4, July, 672. 



VULCANIZING OF CAOUTCHOUC AT COMMON TEMPERATURES. 



The following process devised by Gaulthier de Caulbry is 

 claimed to effect this object. If an intimate mixture is made 

 of flour of sulphur and dry chloride of lime, a decided odor 

 of chloride of sulphur will shortly be noticeable, while simul- 

 taneously the temperature of the mixture is appreciably ele- 

 vated, and the mass becomes plastic by the softening of the 

 sulphur. If a mixture of this kind, in which the sulphur is 



