Materials and Formulas. 155 



pump the mixture back into itself while hot. This always 

 emulsifies at once, and is permanent with hard as well as soft 

 water. This is diluted with twice its bulk of water before use. 

 The objection to a large amount of water sinks before the fact 

 that this secures a sure and permanent emulsion, even though 

 diluted with hard water. This also becomes, with certain 

 soaps, lumpy and stringy when cold, so that it cannot be 

 readily diluted with cold water unless first heated. Yet this is 

 true with all hard soap emulsions in case of certain soaps. We 

 can, however, always dilute easily if we do so at once before the 

 emulsion is cold, and we can also do the same either by heating 

 an emulsion or diluent, no matter how long we wait." (Page 81). 

 Hubbard-Riley Kerosene Emulsion. 



Hard soap 5 pound. 



Kerosene 2 gallons. 



Boiling soft water 1 gallon. 



The soap should first be dissolved in the boiling water, after 

 which the kerosene is added, and the two churned for five or ten 

 minutes. One essential condition of success in making this 

 emulsion is that the liquids should be as warm as possible. My 

 own practice has been to heat the two after the kerosene has 

 been added, taking care that the oil did not catch fire. It is 

 also necessary that the water be as soft as possible, for if much 

 mineral matter is present the emulsion will not be permanent, 

 and the oil will soon separate and rise to the surface. With 

 very hard water it is almost impossible to obtain a good emul- 

 sion. 



If these conditions are all fulfilled, however, this emulsion is 

 an excellent one, as the amount of kerosene used is large, and 

 in other respects the preparation is easily handled. It should 

 be diluted with from 4 to 20 parts of water before being ap- 

 plied, hard water being again avoided. When diluted with 4 

 parts of water, the emulsion contains about 29 per cent of kero- 

 sene ; when diluted with 20 parts of water it contains nearly 

 9 per cent of the oil. 



KEROSENE EMULSION AND ARSENITES. The attempt has 

 frequently been made to obtain a uniform mixture of these two 

 materials, but with only partial success. The results have not 

 been satisfactory, and the use of such a mixture cannot be ad- 



