662 Journal of Agricultural Research vol. vi, no. i 7 



virus solutions to which several cubic centimeters of ether, chloroform, 

 or toluene have been added did not lose their infectious properties after 

 several months. Carbon tetrachlorid also appears to be quite as inert 

 when added to virus solutions. In a test with this material, 3 c. c. 

 were added to 22 c. c. of virus. The supernatant virus, when tested one 

 month later, was quite as infectious as the untreated. 



In other experiments the mosaic sap has been evaporated to dryness 

 at room temperatures in beakers and the residue treated with ether for 

 several days. Under such conditions, however, the residue is only slightly 

 soluble in the ether and there remains a heavy, gummy, more or less 

 impermeable mass. When the ether was evaporated and the residue 

 again taken up with the original amount of water, the solution was still 

 infectious. 



Although Clinton (8, p. 415) states that the virus can be preserved 

 for a long time by adding to it a small amount of toluene, the writer's 

 experiments indicate that the virus will retain its infectious properties 

 almost indefinitely without the addition of toluene. With no preserva- 

 tive whatever added, the bottled virus was highly infectious when tested 

 from 12 to 15 months later, although putrefaction had taken place. 



TREATMENT OF VIRUS WITH PRECIPITATES OF HYDROXIDS OF 

 ALUMINUM AND NICKEL 



Precipitation of the virus of the mosaic disease of tobacco by alcohol 

 in 45 and 50 per cent strengths indicates that the precipitate carries down 

 the infective principle, leaving the supernatant solution without infectious 

 properties. Similar precipitation experiments have been carried out, 

 using aluminum sulphate and nickel sulphate in alkaline solutions of 

 virus to obtain the insoluble hydroxids of these metals. In order to 

 obtain approximately 1 gm. of aluminum hydroxid in the precipitate 

 aluminum sulphate and sodium hydroxid were added according to the 

 following equation : 



Al 2 (S0 4 ) 3 .i8H 2 0+6NaOH=3Na 2 S0 4 +Al 2 (OH) 6 +i8H 2 0. 

 4.26 gm. 1.53 gm. 2.72 gm. 1 gm. 



The procedure was as follows: On December 1, 191 5, 100 c. c. of virus 

 X 23 , which had been filtered through paper to obtain a clear solution, 

 were made up to 1,000 c. c. with distilled water, thus diluting the virus 

 but 10 times. First, 4.3 gm. of aluminum sulphate dissolved in a small 

 quantity of water were added to the virus solution and shaken. Then 

 1.5 gm. of sodium hydroxid, dissolved in a small quantity of water, 

 were added and the entire solution shaken and set aside. A very heavy 

 flocculent precipitate of aluminum hydroxid was at once formed. This 

 gradually settled, leaving the supernatant solution perfectly clear. On 

 December 2 the solution was tested with litmus paper and gave a slightly 



