A. H. Lees 



147 



the soap pellicules break and liberate a certain amount of free paraffin. 

 Such an emulsion is therefore unsafe to use. It is thus possible to 

 divide emulsions into three classes : 



1. Dangerous. 2. Unsafe. 3. Safe. 



The first includes those which, hke the | % soap with tap water, 

 de-emulsify on standing. The second, those like 1| % soap with tap 

 water and 20 or 25 % paraffin, which de-emulsify on being sprayed. 

 The third, those like the 2 % soap emulsions, in which no de- 

 emulsification occurs at all. 



Wetting Power of Paraffin Emulsion compared with other 

 Auxiliary Wetting Agents. 



' In the previous portion of this paper the wetting power of paraffin 

 emulsions on a certain artificial surface, American cloth, has been con- 

 sidered. Table III gives the results of the wetting power of some of these 

 emulsions and of other auxiliary wetting agents on certain natural 

 surfaces. 



Table III. Wetting Poiver of Various Fluids. 



American Gooseberry 



Wetting Substance Gooseberry Leaf Sea-kale Leaf 



Water 



Gelatine 1 in 1000 



Gelatine 1 in 10,000 



Casein 1 in 1000 



Casein 1 in 10,000 



Soap i % 



Soap 1 % 



Soap 2 % 



Emulsion 



Soap 1 % 



Paraffin 1 % 

 Emulsion 



Soap 1^ % 



Paraffin U % 

 Emulsion 



Soap 2 % 



Paraffin 2% 

 Emulsion 



Soap 1 % 



Paraffin 5 % 



Emulsion 

 Soap 2 % 

 Paraffin 1 % 



Nearly complete 

 Complete 



None 

 Very slight 



Slight 



Nearly complete 



Complete 



Wets by paraffin but 

 not by aqueous 

 solution 



Complete 



Mildew 



None 



Very slight 



Moderate 



Nearly complete 



Complete 



Nearly complete 



Moderate 



