76 



MAINE AGRICULTURAL EXPERIMENT STATION. I9II. 



cheap and simple instrument called the hydrometer. This con- 

 sists of a hollow glass tube, its lower end terminating in a 

 weighted bulb (Fig. 46). Placing this in a liquid, it sinks un- 

 til the liquid displaced equals its own weight. In light solu- 

 tions, therefore, it will sink deeper than in hea\y or dense ones. 

 The gradations to be read are marked on the scale on the neck 

 of the instrument and are in degrees Beaume or in terms of spe- 

 cific gravity. Some instruments give both scales. The Beaume 

 is the one most generally used. 



These instruments cost about $1.00 and may be had of the 

 Bausch & Lomb Optical Co., Rochester, N. Y., or other deal- 

 ers in scientific apparatus. They are absolutely necessary for 

 the proper use of lime-sulphur solutions. The contents of sev- 

 eral casks from one manufacturer may vary in densit}'', and 

 experiments have shown that home boiled solutions will differ 

 considerabl}" in this respect even when the same amount of ma- 

 terial and time of cooking are employed. 



The solutions should be tested at a temperature of about 60 

 degrees, Fahrenheit. Density should never be determined when 

 the solution is hot. 



The following is a table of dilutions.* 



Table 15. 



Hydrometer Reading 

 Degrees Beaume. 



Number of gallons crater for one gallon concen- 

 trated solution. 



Winter Strength 

 (Insecticide) 



?ummer Strength 

 (Fungicide) 





32 



12 



30 





31 



11 



29 





30 



10 



28 





29 



9i 



27 





28 



9 



26 





27 



8i 



25 





26 



8 



24 





25 



n 



23 





24 



7 



22 





38 



^ 



21 





22 



6 



20 



^Cordley's figures. 



