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IOWA ACADEMY OF SCIENCE 
brated by myself by weighing when filled to the marks, with water 
at 20°. The few centimeters remaining to be added were added 
with a buret. 
In making up the hydrochloric acid solution and at all other 
essential points redistilled water was used. The boiler was of 
copper and it was fitted with a Kjeldahl distilling bulb to pre- 
vent the passage of spray. The condenser tube was of block tin 
and extended well into the receiving bottle. A seal of cotton 
between the tube and the neck of the bottle prevented currents 
of air. The collection of the water was begun only after about 
500 c. c. of water had passed over, so as to eliminate carbon 
dioxide. The water was kept stored in glass stoppered, covered 
bottles till required. 
The concentration of the hydrochloric acid solution thus pre- 
pared was further determined by means of silver chloride, fil- 
tered and weighed in platinum Gooch crucibles in the usual 
manner. In all precipitation and washing about 1 per cent of 
nitric acid was present. The filtrates were measured and usually 
amounted to about 500 c. c., and 1.4 milligrams of silver chloride 
was added to the weight for one liter of filtrate. The portions 
of the acid taken for precipitation were 'weighed. 
In the early part of this work ordinary calibrated burets and 
flasks were used, but changing temperature, want of uniformity 
of drainage and the limit of volume in the case of burets to 
rather less than 50 cc. soon proved their inadequacy, and all 
results thus secured were rejected. In the determination of the 
hydrochloric acid and in all titrations here recorded weighing 
burets were used. They were made by the glass blower at the 
Chemical Laboratory, University of Illinois, at the instance of 
Professor W. A. Noyes to whom I am very greatly indebted. 
They are essentially the same as described by Washburn,^ and 
used by him in his recent work on the value of the Farad. They 
weigh scarcely 50 grains, hold about 175 cc., and have long 
slender delivery tubes to insert into other vessels, and very 
small tips so as to give small drops. 
The following are the results of the determination of the con- 
centration of the acid by means of silver : 
^Journal American Chemical Society, vol. 34, 1358. 
