New YorK AGRICULTURAL EXPERIMENT STATION. 357 
some multiple of 4, as 8, 12, 16, 20, etc. Just how many of 
these compounds may actually be formed, we do not know. 
Theoretically, it is possible to have, at least, the following 
compounds of calcium and sulphur: 
CALCIUM SULPHIDES. 


Parts of Parts of Parts of 
calcium sulphur S for Chemical 

(Ca) by (S) by one part formula Name. 
weight. weight. of Ca. 
| 
Ca S) 
ee TiO th: MME 5 4 i! 0.8 Cas Calcium mono-sulphide 
Ge Sa ne 5 8 1 :1.6 CaSe " di- 5 
Bie aes On 5 119. 1 see A. CaS; ze tri- * 
SOP te. ahs 5 16 1 foie CaS. _ tetra- 7 
Lares ek ae ee 5 20 1 4.0 Cas; . penta- “ 


It will be noticed that the names indicate the relative 
amounts of sulphur in combination. The general name, 
polysulphides of calcium, is often applied to the members of 
this series above the first. Most of these compounds can be 
made, but not all are of practical interest in connection with 
the lime-sulphur preparation. 
When lime and sulphur are boiled together in water, some of 
the compounds mentioned above are formed; the kinds and 
amounts of the compounds thus prepared depend chiefly upon 
the proportions of lime and sulphur, fineness of division, length 
of time the mixture is boiled, etc. The compounds which ap- 
pear to be present in largest amounts in the freshly prepared 
concentrated wash are the fourth (CaS,) and fifth (CaS,). 
These are easily soluble in water, producing an orange-red 
liquid. According to the explanation most generally accepted, 
it is believed that these are the compounds which are most 
efficient in killing scale-insects and that probably the one 
higher in sulphur (CaS,) is more effective that the the lower 
(CaS,), though it is not yet clearly established in just what 
manner the insecticidal action takes place nor to what specific 
compound or compounds it is due. 
The simplest compound of calcium and sulphur (CaS), the 
monosulphide, is a grayish-white solid and is not easily soluble 
