l86 PHARMACEUTICAL BACTERIOLOGY. 



like the ordinary bellows box for blowing insect powder, or modifications 

 of this simple device. A third method known as the sifting method is much 

 in vogue in the cotton fields. The powder is placed in a porous bag or cloth, 

 fastened to a stick and shaken over the plants to be treated. Only three 

 powders are used to any considerable extent, as follows: 



a. Slaked Lime. — Dry air slaked lime is reduced to a uniformly fine 

 powder which is then ready for use. It is very eflScacious with all slimy 

 animals, as slugs and snails. It is appUed to plants when the pests are 

 active, that is, in the early morning or in the evening. Lime is used where 

 paris green is not permissible, as with fruit plants and edible herbs. 



b. Sulphur. — The flower of sulphur or ground sulphur is a very widely 

 used remedy for fungous pests, as mildew; also for the red spider and thrips. 

 Sulphur is active only ia the sunlight, particularly on a hot day. 



The flower of sulphur gives better results than the ground sulphur be- 

 cause it "sticks" better. It should be applied evenly and not too thickly. 

 Remember that sulphur dioxide is very injurious to plants, therefore fumiga- 

 tion by burning sulphur is out of the question. 



c. Paris Green and Other Arsenicals. — These are generally not used in 

 the dry powdered form. When so used they are diluted with flour, dust 

 or other inert powdered material. Must be sparingly applied and evenly 

 distributed, otherwise serious damage may be done to the foliage. 



B. Gases. — Gases diffuse with great rapidity and when applied within 

 an enclosed space will, in a short time, be uniformly distributed throughout 

 the enclosed space. The rapid diffusion of gases is a great hindrance to 

 their practical utilization in the open as in orchards, fields and gardens. 

 Their use is quite limited. 



a. Carbon Bisulphide. — This is not used with growing plants though it is 

 applied to stored seeds, and dry plants and grains, for the purpose of killing 

 insects and other destructive animals. It is also used to kill pests which 

 live in the soil, as the grape Phylloxera. For this purpose a machine is 

 used which injects the bisulphide into the soil. To destroy pests in drug 

 plants, seeds and grain, enclose them in a space, place a dish containing 

 the bisulphide on top of the material. The vapor being heavier than the air, 

 gravitates downward and soon fills the entire enclosed area. The amount 

 necessary to do the work will depend upon the nature of the material to be 

 treated and the tightness of the enclosure. Roughly estimated a dram of 

 the carbon bisulphide to five pounds of the material is sufl&cient. Grain- 

 men usually apply one pound to the ton of grain, if the bin is tight. 



Carbon bisulphide is one of the most effective remedies against the gopher 

 and the ground squirrel. Use the remedy after a rain as the soil is then less 

 porous. Pour an ounce over a rag or other porous substance (horse drop- 

 pings are much used), stuff this into the hole and plug with a ball of dirt. 



