POULTRY DISEASES AND THEIR TREATMENT. 131 



the market which are no more effective than an equal quantity 

 of any inert powdered substance would be. It is not only a 

 waste of money but of time as well to use such powders. At the 

 Maine Station no lice powder has been found that is so satis- 

 factory as that originally invented by Mr. R. C. Lawry, for- 

 merly of the poultry department of Cornell University. The 

 following matter regarding this powder (which can be made at 

 a cost of 5 cents per pound) is quoted from a circular issued 

 by the Maine Station : 



"In using any kind of lice powder on poultry, whether the 

 one described in this circular or some other, it should always be 

 remembered that a single application of powder is not sufficient. 

 When there are lice present on a bird there are always unhatched 

 eggs of lice ('nits') present too. The proper procedure is to 

 follow up a first application of powder with a second at an inter- 

 val of 4 days to a week. If the birds are badly infested at the 

 beginning it may be necessary to make still a third application. 



"The lice powder which the Station uses is made at a cost of 

 only a few cents a pound in the following way : 



"Take J parts of gasoline^ 



"i part of crude carbolic acid; 



"To get the proper results only the po-p§ per cent, carbolic 

 acid should be used for making lice powder. 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 obtain- 

 able 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 now, therefore, 

 modified as follows : 



"Take j parts of gasoline, and 



I part of crude carbolic acid, pO-p3 per cent, strength, 

 or, if the po'p^ per cent, strength crude carbolic acid cannot be 

 obtained take 



J parts of gasoline and 

 I part of cresol." 

 "Mix these together and add gradually with stirring, enough 

 plaster of paris to take up all the moisture. As a general rule 

 it will take about 4 quarts of plaister of paris to i quart of 



