48 



INSECTICIDE STUDIES. 



much to be desired, it at leu>t gi\ >* a])])roximate results when a large 

 portion of the material is used. The borax was determined by the 

 same method as given in Bulletin r>s for similar compounds, except that 

 the ammonia was all driven off from the solution by boiling before the 

 boric acid was determined. 



This mixture would very likely be efficacious in driving away cock- 

 roaches and water bugs, but probably it would not kill them. 



TOBACCO EXTRACTS. 

 % 



The analyses of five samples of tobacco extracts are given in Table 

 XI\ r . In two of these only the most important constituent, nicotin, 

 was determined, while in one of them the determination of this con- 

 stituent was not made. 



TABLE XIV. ('<>mjt<n<ition 



<'.rtr<i<-1x. 



a Specific gravity, 1.3858. 



Specific gravity, 1.37 



Iii the first four of these samples the nicotin figure is much too low 

 for a good tobacco extract; especially is this true of the first two. 



FORMALINS, 



The analysis of three samples of formalin, and the average of the 

 results obtained on five samples, together with one anal made in 

 this laboratory, are given in the following table: 



T \ lil.i: XV. ( 'i>in/Hi*ifinn of Inn/I'll ins. 



Formaldehyde. 



f "> -ample*. 



