W.W. Palmer 123 
hemoglobin per 100 cc. Although the blood of normal men in 
this country, as shown by Meyer and Butterfield (6), Williamson 
(10), and also as we have found by use of the method here de- 
scribed, contains on the average 16.6 gm. of hemoglobin, which 
would correspond to an oxygen capacity of about 22 per cent, it 
was thought best to keep Haldane’s standard for the present. 
It is a simple matter to compute the gm. of hemoglobin in any 
given blood from the results obtained. 
The standard hemoglobin solution is prepared as follows: A 
. quantity of defibrinated human or ox blood is obtained. The 
oxygen capacity is determined by the method of Van Slyke (11). 
The blood may also be standardized by a spectrophotometer or 
solutions made from hemoglobin crystals prepared in the man- 
ner described by Butterfield (8). We have checked several 
times our standard and found that the oxygen capacity method 
for standardization is most convenient and satisfactory. The 
blood is diluted with 0.4 per cent ammonia solution so as to 
make a 20 per cent solution of a blood with an oxygen capacity of 
18.5 per cent. This 20 per cent blood solution is then satu- 
rated with carbon monoxide by bubbling through it illuminating 
gas for 10 minutes. A drop of caprylic alcohol prevents trouble- 
some foaming. The glass tube through which the gas is passed 
into the blood solution is withdrawn slowly and the bottle stop- 
pered immediately. Rubber corks must not be used in con- 
nection with hemoglobin solutions. The cork should be sealed in 
with paraffin and the solution, protected from light, kept in the 
ice chest. Such a solution thus protected will keep for months. 
Several solutions now nearly a year old prepared in this man- 
ner have shown no deterioration. 5 cc. of this 20 per cent blood 
solution made up to 100 cc. with 0.4 ec. of ammonia solution and 
saturated with carbon monoxide, make the 1 per cent standard 
for use in the colorimeter and may be prepared from time to 
time as desired. The 1 per cent standard for routine use may be 
kept in a dark glass or black painted aspirator bottle, the lower 
opening of which is provided with a cork, through which passes a 
glass tube with a ground glass cock for withdrawing small amounts 
of solution. A glass tube is put through the cork in the top of 
the bottle and extends to the bottom. Both corks should be 
sealed with paraffin. This glass tube is connected with an open 
