356 REPoRT OF THE CHEMIST OF THE 
turers whose mixtures were free from sediment. Under the 
circumstances, the fruit-growers were greatly confused and 
came for help to the Entomologist of the Station. In this way 
the general problems for investigation became definite. 
The specific points studied are the following: (1) The liquid 
portion of lime-sulphur preparations, (2) the sediment, (3) the 
influence of purity of lime on the composition and yield, (4) 
the influence of magnesium oxide in lime on the results of the 
preparation, (5) the influence exerted by length of time and 
temperature of heating, (6) effect of adding lime and mag- 
nesium oxide to diluted mixtures. 
The results of the most extensive and careful chemical inves- 
tigations previously carried on in this field are presented by 
Haywood in Bulletin 101, U. S. Dept. Agr., Bureau of Chemis- 
try (1907), and by Thatcher in Bulletin 76 of the Washington 
Station. 
CHEMISTRY OF THE LIME-SULPHUR PREPARATION. 
Before taking up the details of the results of our investiga- 
tion, it is desirable to present a brief consideration of certain 
chemical facts to serve as a foundation for the discussion of 
the results. In connection with this preliminary treatment, we 
shall to some extent anticipate some of our results for the 
sake of illustrating certain statements. 
COMPOUNDS OF CALCIUM AND SULPHUR. 
Calcium is known to form several different compounds with 
sulphur. When a mixture of lime (calcium oxide, CaO) or of 
freshly slaked lime (calcium hydroxide, CaO,H,) and sulphur 
are suspended in water and heated, chemical combination takes 
place; the calcium of the lime combines with the sulphur. One 
peculiarity of the combination of calcium and sulphur is that a 
definite amount of calcium can combine with varying amounts 
of sulphur to form the several different compounds known. 
The numerical combining relations of calcium and sulphur are 
such that 5 parts by weight of calcium (equivalent to 7 parts 
of pure calcium oxide) combine with 4 parts of sulphur or 
