IN CHEMISTRY. 137 



one per cent, phosphate of lime and magnesia, and two 

 per cent, animal matter. The shell would weigh over 

 100 grains, so that a hen laying 100 eggs in a season 

 would require nearly i J Ibs. of CaCO 3 . The hen must 

 in part secrete this from her food, and in part gather it 

 from the sand, pebbles, etc., she picks up amid her inces- 

 sant scratching and searching. 



27. Why will tallow make a harder soap than lard? 

 Tallow contains more palmitin, and less olein, than lard. 



28. Why does new soap act on the hands more than old ? 



The spent lye, which contains the excess of alkali, 

 gradually separates from the soap, leaving only the salts 

 in which the alkali is neutralized by the fatty acids. Also 

 a more complete combination takes place, whereby some 

 free alkali is taken up by the acids, perhaps before un- 

 combined. The former statement is especially true in 

 the case of soft or home-made soap. 



29. What is the shiny coat on certain leaves and fruits ? 

 A species of wax secreted by the plant. 



30. Why does turpentine burn with so much smoke ? 

 Because it contains an excess of carbon. 



31. Why is the nozzle of a turpentine bottle so sticky ? 



The turpentine on exposure to the air oxidizes, turning 

 to rosin. 



32. Why does kerosene give more light than alcohol? 



It contains more carbon, which, when heated in the 

 flame of the burning H, gives out a white light. 



