524 ANNUAL REPORT OF THE Off. Doc. 



The ammonia water used for preparinjj; the copper carbonate solu- 

 tioi. should be of the t^trength designated as "2(> degrees Beaume," 

 tlie ordinary commercial product. Of adulteration, there is little to 

 fear. Sometimes, hoAvevei-, it is weak, owing to llu^ escape of the 

 gas from the sohition (it is simply a solution of ammonia gas in 

 water) when the vessels containing it are not tightly closed. When 

 up to full strength the 2(1 degree ammonia contains about 2~) per cent, 

 of the gas, and it is upon thi.s strength that the ijuantity recom- 

 mended in the formula for prejiaring the solution is based. It should 

 be borne in mind, however, that no more annuonia should be used 

 than is actuall}' necessary to dissolve the copi)er carbonate; the 

 smaller the quantity, the better. Ammonia has an extremely caustic 

 action upon the leaves and when used too strong eterions injury is 

 sure to follow. For this reason it is safest for those who make use 

 of the co])per carbonate solution to any great extent to provide them- 

 selves with a "specific gravity spindle" for testing the ammonia they 

 intend to use. Fig. 4 represent® such an instrument in use. A tall 

 cylinder, such as shown in the drawing, is filled with the ammonia 

 water to be tested. The spindle is then allowed to float in the 

 liquid. The depth to which the bulb will sink will depend ujjon the 

 density of the licpiid. The ui)per stem of the s])indle is graduated 

 to show the si)ecific gravities indicated by the dilTerent depths to 

 which the bulb sinkis in the li(iuid to be tested. The figure at the 

 surface indicates the specific gravity, or relative density as compared 

 with water, of the ammonia water being tested. The specific gravity 

 in turn indicates the percentage of ammonia, which can be found by 

 reference to the appended table. For example, if the spindle indi- 

 cates a specific gravity of .1)02, by reference to the column "specific 

 gravity" the figure opposite in the "I'cr cent. of Ammonia" column is 

 found to be 24.!)4, thus indicating that the ammonia water is prac- 

 tically up to strength. If the ammonia is strongei", less will be re- 

 (piired to accomjjlish the solution; if weaker, more must be used. 

 With this test, the fj'uit gi'ower is enabled to determine just what 

 strength of ammonia he has to deal with, and thus all dangerous 

 guess-work can be avoided. 



