26 Modern Fishculture in Fresh and Salt Water. 



Experiment D. A full grown shad {Alosa prcesta- 

 bilis) in a large tub of water, to which 1-400 in bulk of 

 sulphuric acid was added, died almost immediately. 



Experiment E. A similar fish, in a tub of water, to 

 which 1-200 of concentrated solution of soap was added, 

 became uneasy, and turned several times or its side, but 

 at the end of five minutes was still alive and to'-r-bly 

 active. Compare the effect of soap r 



Experiment F. A similar fi^' of water, to 



which 1-200 in bulk of dry c' .. lime was added, 



became violently excited, then exhausted, and at the end 

 of three minutes from the beginning, died from a rup- 

 ture of the gill vessels. 



"In these experiments large proportions of the pois- 

 ons were used, in order to show plainly the eflfect ot 

 each. What the effects would have been on salmon we 

 cannot infer, except that we know, in general, that the 

 trouts are more fastidious than fish like the shad, and 

 are more easily destroyed. A shovelful of powdered 

 quicklime thrown on the water over a shoal of trout, 

 will bring a number of them dead to the surface within 

 ten minutes. Many trout brooks in England have been 

 depopulated by drains from copper mines emptjrjng into 

 them; the insoluble sulphurets sink to the bottom of 

 the brook, where they decompose, giving oflf free sul- 

 phuric acid, which is very destructive. Sawdust is no- 

 toriously pernicious. Its effect is mechanical, bv get- 

 ting into the gills and producing suffocation. Lime is 

 as deadly to salmon as to trout ; gas-works, too, are bad, 

 and the arseniates thrown out from dye-houses are high- 

 ly injurious. City sewage, unless in great quantities, 

 will not drive them away, as is shown by salmon going 

 up the Dee, and past the city of Chester, whose sewers 

 empty into the river. The effect of gas-works depends, 



