436 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



other substances. These two vessels have been again docked 

 in Portsmouth, having in the mean time lain principally in 

 harbor. The test of Jesty's composition was very satisfac- 

 tory. All portions of the sheathing were found to be free 

 from algae or other substances, and remained precisely as they 

 were at the time they were first painted, excepting some very 

 small spots under the stern, where a green slime had formed 

 of the thickness of a sheet of paper. Mitth. Oesterr. Hydrog. 

 Bureau, 1874, 494. 



i 



PKEVENTION OF BOILER INCKUSTATIONS. 



Lesueur proposes the use of metallic zinc as a preventive 

 of boiler incrustation. Twenty kilogrammes, introduced into 

 a boiler of 100 horse-power, is sufficient for at least three 

 months. The zinc disappears, and whatever is deposited from 

 the water forms no crust, but only a loose mass which can 

 easily be washed out. The mode of action is not yet ex- 

 plained, but M. Lesueur supposes electrical force to be in- 

 volved. A galvanic couple may be formed b}'- the zinc with 

 the metal of the boiler, so that a little water would be decom- 

 posed. Thus a film of hydrogen might be produced and con- 

 tinually renewed on the surface of the iron, preventing the 

 adherence of any deposit. Ann. de Ch. et de JPhys. 



APPAKATINE, A NEW ANTI-INCEUSTATOE. 



A new anti-incrustator has lately been introduced under 

 the name of apparatine, which is prepared by stirring np six- 

 teen parts of potato starch in seventy-six parts of water, and 

 then adding eight parts of potash or soda lye, at 25 Baume, 

 the whole to be thoroughly mixed together. In a short time 

 the mixture forms a thick jelly, and it is then beaten up vig- 

 orously for a time, when it forms a colorless, transparent sub- 

 stance, slightly alkaline to the taste, and of a strong glue-like 

 consistency. It dries slowly in the air without decomposition, 

 and when perfectly dry resembles horn, but is more flexible. 

 When introduced in small quantity into steam-boilers it pre- 

 vents their incrustation. It is also capable of nearly all the 

 applications of ordinary gelatin, and is especially adapted 

 for sizing textile goods of all kinds, imparting to them a 

 hitherto unattained smoothness. When once applied to 

 goods and dried it is perfectly insoluble, as three or four 



