II.] CALCIUM CYANAMIDE 41 



exaggerated. It is best to mix the cyanamide with 

 superphosphate before application to the land ; in most 

 cases when cyanamide is used phosphates will also be 

 required, and a mixture of cyanamide with from five to 

 ten times its weight of superphosphate can be con- 

 veniently made and forms a good fertiliser for barley 

 or turnips. The mixture should be made on the 

 floor of the manure shed at least a day before the 

 manure has to be sown ; if the cyanamide is care- 

 fully handled and covered with superphosphate, it 

 can be mixed without creating an unbearable dust. 

 With the slaking of the lime a good deal of heat is 

 developed and the manure begins to steam, but a 

 sprinkling from a watering pot will help to keep the 

 heat down without rendering the mixture in any way 

 difficult to handle. The heap should be turned over 

 two or three times to secure a good mixture, and left 

 until the next day to cool off. It remains in a nice 

 friable condition and undergoes practically no further 

 change if it cannot be sown at once. No unpleasant 

 gases are given off during the mixing ; the samples 

 of cyanamide first made contained some unchanged 

 calcium carbide which gave off acetylene on wetting, 

 but this is now avoided in the manufacturing process. 



Two methods have been adopted to obviate the 

 dustiness ; in one the product is treated with a small 

 proportion of heavy shale or coal oil, in the other just 

 sufficient treatment with steam is applied to convert 

 the quicklime into slaked lime, and give the material 

 a more granular form. This latter process has the 

 further advantage of decomposing any traces of calcium 

 carbide and phosphide that may be present in the 

 original material. A slightly different product con- 

 taining calcium cyanamide is manufactured by a firm 

 in Westeregeln, under the patents of F. Polzenius, by 



