104 



THE PROCESS OF DILUTION OF CONCENTRATED 

 LIME-SULPHUR SOLUTION. 



Prof. J. P. Stewart. 



The following- description and data are from 

 Bulletin No. 99 of the Pennsylvania Experiment Sta- 

 tion prepared by Prof. J. P. Stewart, whose work 

 has been so beneficial to orchardists : 



THE HYDROMETER. 



This is an instrument much like that used in 

 testing acids in dairy work, but with a wider range, 

 and is used in determining the density of the con- 

 centrate preparatory to the dilution. These instru- 

 ments are made in two scales, the specific gravity 

 and the Beaume, both of which may be placed on the 

 same instrument. Densities are expressed by the 

 former in decimals and by the latter in degrees. The 

 Beaume scale is somewhat easier to read, but the 

 other is more convenient to use, inasmuch as the re- 

 ciuired dilutions can be obtained more directly from 

 it. A desirable range is from 1,000 to 1.32 or 1.35 on 

 the specific gravit}^ scale or from o to 35 degrees or 

 38 degrees Beaume. Such instruments have been 

 put up according to these specifications and are de- 

 scribed herein. They are simple in use and indis- 

 pensable in the accurate dilution of concentrated so- 

 lutions. 



THE PROCESS OF DILUTION. 



In the application of any concentrate, either home-made or commercial, 

 it is essential that a definite method of dilution be followed. Two solutions 

 may look exactly alike and yet differ widely in density, so that any accurate 

 method must be based primarily on the density of the concentrate that is being- 

 diluted. ]\Ioreover,, we believe that recommendations based on the density 

 of diluted spra}" are preferable to those based on the number of dilutions, 

 even when accompanied by a statement of the concentrate's density. 



Accrirate dilution is very simple and easily accomplished with the aid of 

 a hydrometer having a specific gravity scale. (The presence of foreign 

 soluble materials or of much roily sediment in the sample will vitiate the test, 

 a fact which must be taken into account — the former especially in solutions 

 of unknown preparation. Also, for exact work the temperature of the con- 

 centrate should be within about 10° of that stated on the outside of the 

 instrument.) Sprays of any desired density may be obtained from any com- 

 centrate by simply getting the reading of the concentrate and dividing the 

 decimal of this reading by the decimal of the spray desired. For example, 

 if the reading of the concentrate is 1.27 (about 31° Beaume), to get a spray of 

 1.03 density we divide the .27 by .03 and obtain 9, which is the number of 

 dilutions required and which of course is obtained by adding eight volumes 

 of water. In this ve are snnply applying the general fact that the density of 

 the solution heavier than water varies inverselv with the number of dilutions. 



