MAINE AGRICUI.TURAL EXPERIMENT STATION. /I 



The most efficient lice powder known to the writer is that 

 invented by Mr. R. C. Lawry, formerly of the Poultry Depart- 

 ment of Cornell University. This powder is made by incorpo- 

 rating the liquid mixture of 



3 parts of gasoline 



I part of crude carbolic acid 



in sufficient plaster of paris to take up all the moisture. 



Twe difficulties have arisen regarding the practical utility of 

 the powder as above described. In the first place a great many 

 druggists appear to have a deep-seated and ineradicable preju- 

 dice against furnishing their customers crude carbolic acid at 

 any price. Reports have reached the vStation of druggists mak- 

 ing such utterly preposterous and absurd claims as that carbolic 

 acid is a highly explosive substance, which they do not dare to 

 handle ! In the second place difficulty has arisen over the fact 

 that there are in the drug trade three grades of crude carbolic 

 acid. Two of these are very much weaker than the other and 

 are quite useless for making the lice powder. The three grades 

 are listed as follows by a reputable chemical house. These are 

 retail prices. 



Acid Carbolic, Crude, per gallon 25c. 



Acid Carbolic, Crude 50-60 per cent., per gallon ^oc. 

 Acid Carbolic, Crude 90-95 per cent., per gallon 50c. 



To get the proper results only the QO-of, per cent, should be 

 used for making lice powder. ' The weaker acids are ineffective. 



Owing to the difficulty in getting the strong crude carbolic 

 acid locally in this State at reasonable prices, the Station has 

 experimented to see whether some other more readily obtainable 

 substance could not be substituted for it. It has been found that 

 cresol gives as good results as the highest grade crude carbolic. 



The directions for making the powder are, therefore, modified 

 as follows : 



Take j parts of gasoline, and 



I part of crude carbolic acid, po-Qj per cent, strength, 

 or, if the po-Qfi per cent, strength crude carbolic acid cannot be 

 obtained take 



J parts of gasoline and 



I part of cresol. 



