BISULPHIDE OF CARBON, 



29 



Tabular statement showing results of experiments in poisoning small mammals with 



bisulphide of carbon. 



No. 



Species. 



Distance 



from 

 mouth of 

 burrow. 



Diameter 

 of burrow. 



Amount of 

 bisulphide. 



Time. 



1 





Inches. 



154 

 99 



120 

 51 

 14 

 14 

 14 



Inches. 

 4 

 5| 



Cubic cm. 

 49 

 49 

 49 

 49 

 29 



Min. 

 8 



71 



do 



5 



3 



do 



5 



4 



..do 





6 



5 



do 





(*) 



a 







6 



7 







83 

 18 



(t) 



8 







6 



q 





60 

 9G 

 48 

 120 

 6 







10 



do 





36 

 29 

 44 

 29 



6 



11 



do 





9 



W 



do 



2 



§10 

 *6 



13 



do 













* Vapor passed by and did not completely fill burrow. At end of time the animal was anaesthetized, 

 but revived, 

 t Anaesthetized in five minutes; revived three hours later. % Not quite dead. § Not affected. 



Prof. E. W. Hilgard, of the University of California, deserves the 

 credit of originating the bisulphide method of destroying burrowing 

 mammals. In a bulletin l On the destruction of Ground Squirrels by 

 the use of Bisulphide of Carbon,' published in 1878, he gives the 

 results of experiments made on the California Ground Squirrel (Spermo- 

 philus beecheyi) as follows: 



" It is hardly necessary to enlarge upon the importance to California 

 agriculture of devising some ready, safe, and effectual means of put- 

 ting ah end to the constantly increasing inroads of the ground squirrel 

 upon the grain fields and pastures of the State. Unlike most other 

 wild animals, whose range diminishes as culture advances, the ground 

 squirrel finds an improvement of the conditions of its existence as the 

 area of cultivation increases. Each year we hear of its taking pos- 

 session of < fresh fields and pastures new,' while rarely loosening its 

 grip upon any district once invaded; and the tax it levies upon the 

 grain-growers of some counties exceeds all the other taxes combined. 

 The damage done during the past season in Contra Costa County alone 

 was estimated bj 7 the board of supervisors of that county at not less 

 than $150,000, while in many individual cases from 30 to 50 per cent of 

 the crop was harvested by the squirrels before the reaper could take 

 the field." 



After describing the properties of bisulphide of carbon and some of 

 its uses he goes on to say : * 



" It is curious that in no case have I known a squirrel to run out of 

 the holes before the gas; when it meets it face to face in a run, death 

 seems to be almost instantaneous. But inmost cases the animals seem 

 to retire to their nests to die there in a stupor. The mode of proceed- 

 ing is simply this: Select one or two of the freshest holes in a burrow, 

 introduce into it, as deep down as you can reach, a wide-mouthed ounce 

 vial full of the liquid, upset the vial, and withdraw it. * * * The 

 Jioles may all be closed at once, with earth, which need not be rammed j 



