52 
air passed tlirough the serum was kept as nearly as possible at 33° C. ; 
it never exceeded 35° C. The evaporation proceeded with fair 
rapidity. At the beginnino- there was some frothy bubbling, but that 
soon subsided. The entire lot of serum was dried in ten and a half 
hours, drying in large sugardike flakes. Very little adhered to the 
side of the tube and there were no hard cakes. 
The dried serum weighed 25 grams and was readily powdered in a 
sterile mortar to break up the larger lumps and then placed in a spe- 
cial porcelain grinder with porcelain balls and rotated for several 
hours. About half a gram of the powdered serum was planted in a 
tube of bouillon, which showed no growth at the end of four da vs. 
Horse Xo. 590: This horse was also bled on two succeeding da vs — 
June 20 and 21 — six liters being taken at each bleeding, as before. 
The 2d tubes, each containing half a liter of blood, were placed in a 
room with a temperature of approximately 25° C. After clotting- 
two days the serum was poured oli, only the perfectly clear fluid 
entirelv free from coloring matter being retained. From the 12 
liters of blood. d,127 c. c. of serum were obtained. Samples were at 
once taken and tested for purity and potency, as before, with satisfac- 
tory results. 
As soon as the samples were taken. dO c. c. of pure chloroform were 
placed in the bottle with the serum, which was placed in the ice box 
at 1.7° C. Upon the same day evaporation of the serum was begun, 
proceeding as above described. 
The evaporation of this amount of serum required 25 hours, the 
temperature of the air and water bath being the same as before. This 
serum dried in large golden-colored flakes, which were partly pow- 
dered in the sterile mortar and then put into the ball grinder and 
reduced to a fine, almost impalpable powder. 
Four hundred and five grams of the dried serum were obtaiii^d. 
Half a gram was planted into bouillon, which showed no growth in 
three davs. indicating that it had remained free from contamination 
throughout the operation. 
Bottling and preseri'ing the serum . — The dried serum must be kept 
guarded under special conditions to prevent deterioration. The oxy- 
gen of the air must be excluded in order to retard the process of oxi- 
dation, which rapidly alters the antibodies, especially under the influ- 
ence of light. The serum is, therefore, always kept in absolute dark- 
ness. 
The serum must be perfectly dry. It is therefore kept under the 
influence of phosphoric anhydrid, (PgOjj, as shown in the accompany- 
ing illustration (tig. 8). Further, the serum is kept in a specially built 
ice box, maintained at a constant temperature of 5° C. by means of 
circulating brine. 
