New York AcrIcuLTURAL EXPERIMENT STATION. 213 
PREPARATION OF STANDARD SOLUTIONS OF ACIDS. 
A solution of N-10 HCl was standardized by the official silver 
chloride method.t’ A solution of N-1o NaOH was then prepared 
by titration. By means of this, N-1o solutions of other acids were 
prepared. The acetic and lactic acids used were of the highest 
quality manufactured by Kahlbaum; the hydrochloric and sulphuric 
acids were of the purest grade made by Baker & Adamson. Only 
water of less than 2.2 X I0-® conductivity was used in making uss 
standard preparations of acids. 
MEASURING SOLUTIONS FOR USE. 
In measuring the solutions, carefully calibrated pipettes were 
used and the solutions were delivered into the flasks with the 
smallest possible amount of exposure to the air. 
PREPARATION OF CONDUCTIVITY WATER. 
Water of conductivity as low as I X 10-® was prepared by treat- 
ing ordinary distilled water with a mixture of sulphuric acid and 
potassium bichromate and then distilling. To a 12-gallon carboy of 
ordinary distilled water (of conductivity equal to 15 to 18 X I0-®) 
we added in water solution 20 grams of potassium bichromate and 
20 cc. of concentrated sulphuric acid, and then allowed the water 
thus treated to stand about 24 hours before distillation. This was 
performed with a retort of Jena glass, arranged in the manner de- 
scribed by Hulett? Four liters of the treated water were placed 
in the retort and the first three distilling over were collected in a 
Jena glass flask. The conductivity of the first liter of distillate was 
generally 1.0 to 1.2 X 10-®, and of the third, 1.5 to 1.8 10%. A 
condensing tube of glass, after several liters had been distilled 
through it, gave as pure water as we were able to get with a block- 
tin tube. It was found unnecessary to redistil the water from 
barium hydroxide, since the laboratory distilled water appeared to 
contain practically no carbon dioxide. 

*U. S. Dept. Agr., Chem., Bul. No. 46. 
? Ztschr. Phys. Chem., 21:297. 18096. 
