REAGENTS 
35 
Formulas for Alcohols.—The following formulas will enable 
anyone to make the other grades of alcohol from 95 per cent alcohol 
and water. 
95 
95 
95 
95 
95 
95 
95 
95 
95 
10 
15 
20 
30 
40 
50 
60 
70 
85 
85 
80 
75 
65 
55 
45 
35 
25 
10 
The foregoing are the formulas for various alcohols from 10 to 
85 per cent. The first column shows the formula for making 10 per 
cent alcohol. The percentage of alcohol secured in each case is 
indicated by the middle number in each column. In the first formula, 
subtract 10from 95; the result, 85, is the number of cubic 
centimeters of water which must be added to 10 c.c. 
of 95 per cent alcohol in order to obtain 10 per cent 
alcohol. The mixture contains 95 c.c. of 10 per cent 
alcohol. If more or less than 95 c.c. of the mixture is 
needed, take proportional parts of 10 and 85. This 
simple method is a time-saver, but if the bottles or 
Stender dishes are to be filled frequently, it will be a 
still further saving of time to use a long label (Fig. 15) 
and, after pouring in the 95 per cent alcohol, draw a 
line showing how high it reaches; and then, after pour¬ 
ing in the water, draw another line. The next time 
it is necessary to fill the bottles merely pour in 95 per 
cent alcohol until it reaches the first line, and then 
pour in water until it reaches the second line. It is 
not necessary to use distilled water if pure drinking-water is available. 
Synthol is used like alcohol, and many believe it to be a good 
substitute. 
Acetone has also been used with more or less success for all 
grades except absolute alcohol. 
Some investigators use more or less complicated diffusion appa¬ 
ratus and make the dehydration process extremely gradual. Judging 
from the finished preparation, we find no advantage in the method. 
In the diffusion process, the solution is constantly changing. This 
may not be an advantage. 
Some very minute objects, like bacteria and the smaller Cyano- 
phyceae, may be dehydrated by heating them until all water is 
70 
per cent 
Fig. 15.— 
Label for 
staining-dish. 
