24 
BULLETIN 879, V. S. DEPARTAIEXT OF AGRICULTUEE. 
CHEMICALS AS VIRUS DISINFECTANTS FOR THE HANDS. 
In addition to the work with chemicals in direct combination 
with mosaic juices, further tests were made to determine the value 
of various solutions as disinfectants for the hands after handling 
mosaic plants. In these tests the hands were smeared with the juices 
of a mosaic cucumber plant and then rinsed in the solution to be 
tested. The healthy plants were then handled in such a way as 
to bring the hands in contact with slight wounds, the fruits present 
were picked, small shoots were pinched off, and other wounds made. 
Formaldehyde, copper sulphate, phenol, and mercuric chlorid were 
all used in weak solutions, as shown in Table VI, and in addition a 
strong soap solution and a mere rinsing of the hands in distilled 
water were tried. 
Table XI. — Value of various chemicals as hand disinfectants after handling mosaic 
cucumber plants. ± 
Date inocu- 
lated. 
'hemieals and strengths used as disinfectants. 
Number 
of plants 
handled. 
Results. 
Number 
of mosaic 
plants. 
Date ob- 
served. 
Aug. 17, 1916 Formaldehyde 1 per cent. 
"Do Formaldehyde 2 per cent. 
Do Phenol 2 per cent 
Do Phenol 5 percent 
Do HgCl 2 1:1,000 
Do Soap and water 
Do Distilled water 
Do Untreated mosaic juices . 
Aug. IS, 1917 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Formaldehyde 1 per cent. 
Phenol 1 per cent 
CuSO.il percent 
HgCl 2 1:1,000 
Soap and water 
Distilled water 
Untreated mosaic juices . . 
Aue. 26, 1916 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Aug 28. 1917 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
As no infection occurred after any of these treatments, it is probable 
that the dilution effect is as important as that of chemical action. 
Hands covered with the juices of mosaic plants, however, gave a high 
percentage of infection when no wash was used. 
EFFECT OF FILTRATION ON THE VIRUS. 
Berkefeld filter. — The presence of a filterable virus as the causal 
factor in cucurbit mosaic has already been demonstrated. Both 
Jagger (17) and the writer (11) have shown that the juices of mosaic 
cucumber plants retain their power of infection after passing through 
a Berkefeld filter. 
The work on this phase of the problem has been continued by the 
writer, using both the Berkefeld and the Chamberland types of filters. 
In the tests with the Berkefeld filter the juices of mosaic cucumbers 
were expressed and passed through double filter paper. After this 
