K. DOMESTIC AND HOUSEHOLD ECONOMY. 457 



careful inquiry has shown, first, that there is no increase of 

 heat; second, that a loss of heat always follows addition of 

 water; third, that both the amount of heat and the tempera- 

 ture of the fire are considerably diminished. 21 A, April, 

 1874,397. 



TESTING MILK. 



As a result of investigations, Professor Sacc proposes, as a 

 test for the dilution of milk, mixing it with its volume of al- 

 cohol of 70 TV., when, with pure milk, the coagulum formed 

 will equal the milk in volume, and will invariably rise to the 

 top. 14 (7, CCXL, 247. 



GUMMED ADHESIVE PAPER. 



Paper recently introduced into the market in sheets, half 

 of which are gummed on both sides, and the other half on 

 one side, and divided into strips and squares of different 

 sizes by perforations, like sheets of postage-stamps, promises 

 to be very convenient in many ways the doubly gummed 

 answering for fixing drawings in books, labels on glass, etc. 

 It is stated that the mixture by which it is coated is pre- 

 pared by dissolving six parts of glue (previously soaked for 

 a day in cold water), two parts of sugar, and three parts of 

 gum arabic, in twenty-four parts of water, by the aid of heat. 

 15 C, 1874, vi., 95. 



PROTECTION OF MAPS, PICTURES, ETC., BY AN INSOLUBLE 



COATING. 



Coat a plate of glass thinly and uniformly with a warm 

 mixture of one quarter of an ounce of ox-gall and one quart 

 of a solution of glue, which will form a stiff jelly on cooling. 

 When the film is well set, render it insoluble by immersion 

 for two or three hours in a solution of acetate of alumina, 

 which may be formed by dissolving one ounce each of alum 

 and of acetate of lead in a pint of water, and decanting the 

 clear liquid from the sulphate of lead formed. Then wash 

 and rinse well, and give it an additional thin coating with 

 weaker glue solution, and lay the picture, slightly but uni- 

 formly moistened, upon it, face downward ; smooth out by 

 gentle rubbing, place in a warm room three to four days, and 

 remove from the glass, when thoroughly dry, by cutting the 



U 



