No. 7. DEPARTMENT OF AGRICULTURE. 359 



ample, recently the Cumberland Valley Railroad Company, with the 

 co-operation of the Division of Zoology of the Department of Agri- 

 culture, ran a demonstrntion train all over their line in Pennsyl- 

 vania, extending over a period of nearly a month, educating thou- 

 sands of farmers and fruit growers in the use of material and ap- 

 paratus for the suppression of the San Jos6 Scale and other pests. 

 The Pennsylvania Railroad Company is at present arranging to 

 run a similar Demonstration Train over its lines in this State. De- 

 tails of the plans w'ill be announced in the newspapers and other- 

 wise, and the co-operation of the members of this Board, their 

 friends, and the public in general is invited in order to make this 

 important work available and useful for the fruit-growers and far- 

 mers of our State. 



GASEOUS AND VOLATILE SUBSTANCES IN FIGHTING IN- 

 SECT PESTS. 



By PROF. FRANKLIN MENGES, Entomologist. 



For a number of years nurserymen and grain elevator owners have 

 been wanting a gaseous or an easily volatilized insecticide that 

 would effectually destroy insects and drive out rodents, while at the 

 same time it would not be inflammable, explosive, objectionable in 

 odor, or poisonous to man or beast. Until recently hydrocyanic 

 acid gas was used for the gaseous substance, and carbon bisulphide 

 as the easily volatilized liquid. Hydrocyanic acid is so extremely 

 poisonous that many nurserymen who have been in the business for 

 years fear to use it, and for the majority of farmers its use would 

 be out of the question, because only a small whift" inhaled might be 

 fatal. For fumigating grain infested with insects it cannot be used 

 at all, because a little of it would poison a whole bin. 



Another thing: Nurserymen who use hydrocyanic acid for fumiga- 

 tion, frequently receive small orders out of season, for which they 

 cannot w(-ll afford to start a large fumigating plant such as is 

 usually connected with a nursery, and therefore it is not only dan- 

 gerous, but inconvenitnt. The easily volatilized liquid that has been 

 used for fumigation is carbon bisulphide. This liquid is poison- 

 ous, inflammable, explosive and highly objectionable in odor — so 

 much so that a rotten egg would be perfume in comparison. If in 

 place of these poisonous substances, and their other objectionable 

 features, we could get a substance that would as effectively destroy 

 these insects without any of the objectionable features, it would be 

 a valuable addition to insecticides. A chemical having these quali- 

 ties, has been in existence in the chemists' laboratory for a long 

 time and has been used as a solvent. Its insecticidal qualities, 

 however, have only recently been discovered. 



Tetrachloride of carbon is a colorless liquid heavier thnn air, and 

 boils at 163 degrees Fahrenheit. It is somewhat related to chloro- 

 form. Instead of having an objectionable odor, it has a pleasant 

 one. It is not inflammable or exj)losive, and is only slightly poiS'On- 



