Polytechnic Association Proceedings. 787 



coal be made the carrier of gaseous bodies suited for the treatment 

 of certain forms of disease; but which, under all ordinary methods, 

 are either impossible or very difficult to administer. The results 

 of experiments he had already made in this direction, were very 



encouraging. 



WHITE PASTE. 



Thi London Photographic News states that a good white paste, 

 pure in color and adhesive to all surfaces, may be made as follows: 

 A solution of two and a half ounces of gum arabic in two quarts of 

 warm water is thickened to a paste with wheat flour; to this is 

 added a solution of alum and sugar of lead, seven hundred and 

 twenty grains in each water; the mixture is heated and stirred 

 about to boil, and is then cooled. It may be thinned if necessary, 

 with the gum solution. 



PHOTOGRAPHING CHILDREN. 



Mr. H. J. Fellows gives, in The Philadelphia Photographer, a 

 simple and eflective remedy for the difficulty of obtaining sufficient 

 time upon children's pictures. He heats the developer. To do 

 this he turns up the edge of a quarter metal plate, so that it will 

 hold just sufficient for one development, and then heats it over a 

 gas flame. By this means he has frequently obtained a picture in 

 ten seconds. It may perhaps lack softness and depth, but what can 

 one expect from a child who will not sit still. 



THE CAMPHOR STORM GLASS. 



Mr. C. Tomlinson, of London, after a series of experiments, arrived 

 at the conclusion that the storm glass was not acted on by light, 

 or atmospheric electricity, or wind, or rain, &c., but solely b}'^ vari- 

 ations in temperature; that is, it is a rude kind of thermoscope, 

 vastly inferior to our ordinary thermometer, and has no meteoro- 

 logical value whatever. His position may be proved by dipping a 

 piece of filtering paper into ether, and placing it on to a bottle 

 containing a little camphor, &c., the cold thus generated will deter- 

 mine a deposit of crystals to any part of the glass at pleasure, and 

 according to any pattern or device we may choose to give the filter- 

 ing paper. 



TO CUT GLASS. 



Broken glass may be utilized, and broken bottles be turned to 

 useful jars, by a simple means of cutting glass, which consists in 

 first scratching it with a diamond or file on the curved or straight 



