Popular Science Monthly 



735 



Poison Gas forAmerican Pests 



GAS that is far deadlier 

 than the poison gases 

 that are used on the battle- 

 fields of Europe is employed 

 daily in America for pur- 

 poses of stamping- out pes- 

 tilential beetles, moths, and 

 vermin of all kinds. Hydro- 

 cyanic acid gas will kill a 

 man if he inhales a single 

 lungful. Yet its deadliness, 

 when controlled by man ami 

 directed against his many 

 small destructive enemies, is 

 so desirable that the Depart- 

 ment of Agriculture has is- 

 sued an order requiring cit- 

 rus crop growers in Califor- 

 nia to apply it to their plants 

 to combat scale, the mealy 

 bug and similar destroyers. 



The gas is produced by dropping tab- 

 lets or measured amounts of cyanide of 

 sodium into sulphuric acid. The room 

 in which the gas is generated is well 

 sealed. Different plants require differ- 

 ent amounts of the gas for thorough fu- 



A Fire-Fighting TroUey-Car 



DULUTH has a fire-fighting trolley- 

 car which is used for detached sub- 

 urbs where poor roads or other barriers 

 prevent ready response by motor or 

 horse equipment to alarms of fire. The 

 harbor of Duluth is formed by a narrow 



Preparing 



A suburban fire department which finds an old street- 

 car an efficient motor fire-engine 



to rid a greenhouse of insect pests by means 

 of deadly gas 



migation, the dose of sodium cyanide 

 varying from five ten-thousandths to 

 five thousandths of an ounce per cubic 

 foot of air space. The former amount 

 is sufficient to kill ordinary green flies; 

 the latter will deal death to sow bugs. 



strip of land extending across the west- 

 ern end of Lake Superior. This strip 

 of land, four hundred to six hundred 

 feet in width, extends for a distance of 

 seven miles from the jMinnesota to the 

 Wisconsin shore. About three miles of 

 it, extending from the Duluth shore, is 

 built up with summer houses and perma- 

 nent residences of expensive 

 construction. This suburb, 

 Park Point, is so narrow 

 that only one street is laid 

 out, and on this street the 

 track is laid. 



The city purchased a 

 streetcar which had out- 

 lived its usefulness, but 

 which was still in fairly good 

 condition. After the seats 

 were removed a hose-box 

 was installed the whole 

 length of the car and left 

 open at both ends, so that no 

 matter in which direction 

 the car is going, it can 

 carry the hose line from the 

 hydrant to the place where 

 the fire is located. 



