54 Preparation of Substances 



Second, as the liquid becomes concentrated 

 the calcium thiosulfate breaks down forming 

 the insoluble calcium sulfite liberating one 

 atom of sulfur, 



CaS203 = CaSOs -h S. 



This reaction may be taking place in this 

 experiment when the volume of the liquid is 

 reduced to about 200 cc. The insoluble cal- 

 cium sulfite remains as a sediment. Third, 

 the sulfur liberated from the thiosulfate unites 

 with the tetrasulfid forming pentasulfid, 



CaS4 -f S = CaSo. 



Thus the composition of the mixture 

 changes during concentration. The amounts 

 of thiosulfate and tetrasulfid become lessend 

 and the quantity of pentasulfid increased. 

 Such changes are considerd desirable and 

 have been effected in most of the commercial 

 preparations on the market. 



Combination sprays may be made by mix- 

 ing Ume-sulfur with arsenate of lead or 

 nicotine sulfate, or both, and simultaneously 

 kill chewing insects and aphis, as well as 

 prevent attacks of fungus diseases. 



Professor Schaefer, of the Michigan Agri- 

 cultural College, states that the action of 

 lime-sulfur solution upon the San Jose scale 

 is one of suffocation; that the caustic liquid 



