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in the one case strong enough to kill all the birds in 

 the London shops, or in the other so great in amount 

 that it would require a Zooful of birds to swallow the 

 solution containing it. 



Extensive and elaborate experiments in this 

 direction have been carried out by Dr. Clarke, and, as 

 my own have been much too limited to be of any 

 value, I shall draw upon his results as given in the 

 lecture from which I have more than once quoted. 

 Without going into particulars of the technique of 

 these experiments, for they would take up many of 

 our pages, I will briefly say that in addition to the 

 fruitless use of various drugs on sick birds in ordinary 

 medicinal doses, the}' were directed to the elucidation 

 of what precise percentage of the different chemicals 

 was needed to prevent the growth of septic bacteria in 

 a given weight of dried hard boiled egg phts a given 

 amount of boiled water, treated at a temperature of 

 loo*^ Fahrenheit. Some of the results were rather 

 surprising, substances generally supposed to be very 

 powerful having but very little effect. For instance, 

 carbolic acid was found to be comparatively feeble, 

 since no less than lo per cent, was required to ensure 

 sterility. " On the other hand, so little as i per cent. 

 " of boric acid .... may be relied on to entirely 

 *' prevent the growth of bacilli in egg .... Sanitas, 

 *' which has been vaunted as a cure for the disease in 

 " such ridiculous quantities as two or three drops to a 

 *' bottle of drinking water, has ver\' little effect on 

 "septic organisms — they grew freely when it was 

 "added in quantities up to 25 per cent., no less than 

 "a quarter of the whole mixture being pure Sanitas; 

 " and even with 30 per cent, the growth of bacteria 

 " was not completely arrested." 



The most effective germicides were of course the 

 biniodide and the perchloride of mercury, the latter 

 of which is known as Corrosive Sublimate. Of either 



