650 



THE POPULAR SCIENCE MONTHLY. 



NON-CONDUCTORS ONE INCH THICK. 



Still air 



Confined air , 



" " = 310 



Wool = 310 



Absorbent cotton , 



Raw cotton , 



it u 



Live-geese feathers = 310 



u (i 



Cat-tail seeds and hairs 



Scoured hair, not felted 



Hair-felt 



Lampblack = 310 



Cork, ground 



Cork, solid 



Cork charcoal = 310 , 



White-pine charcoal = 310 



Rice-chaff , 



Cypress (Taxodium) shavings 



" " sawdust 



" " board 



" " cross-section 



Yellow poplar (Liriodendron) sawdust. . . . 



" " " board 



" " " cross-section 



" Tunera " wood, board 



Slag wool, best 



Carbonate of magnesium 



Calcined magnesia = 310 



" Magnesia covering," light 



" heavy 



Fossil meal = 310 



Zinc white = 310 



Ground chalk = 310 



Asbestus in still air 



" in movable air 



Dry plaster of Paris = 310 



Plumbago in still air 



" in movable air = 310 



Coarse sand = 310 



Water, still 



Starch jelly, very firm, " 



Gum-arabic mucilage, " 



Solution sugar, 70 per cent, " 



Glycerin, " 



Castor oil, " 



Cotton-seed oil, " 



Lard oil, " 



Aniline, " 



Mineral sperm oil, " 



Oil of turpentine, " 



ments. For steam-pipes there have been many more or less suit- 

 able coverings in the market. But one should receive with much 

 allowance the representations of dealers, who sometimes continue 

 to advertise what has been proved to be of inferior value. Not 

 uncommonly they are anxious to sell that on which they can make 

 the most profit rather than that which is most efficient. 



