100 THE FLOATING-MATTER OF THE AIR. 



munication to the Royal Society on January 13, he had 

 successfully worked with temperatures lower than those 

 within my reach in Albemarle Street. There I followed 

 his directions, adhered strictly to his prescriptions ; but, 

 taking care to boil and seal the liquids aright, his results 

 refused to appear in my experiments. On learning this 

 he raised an objection as to temperature, and made a 

 new demand. With this I have complied ; but his posi- 

 tion is unimproved. 



With regard to the question of concentration, I have 

 already referred, in sections 3 and 16 of this memoir, 

 to the great diversity in this particular presented by 

 all my infusions, through their slow evaporation. 

 But more than a general conformity to prescribed con- 

 ditions was observed here also. The strength of an 

 infusion is regarded as fixed by its specific gravity ; 

 and I have worked with infusions of precisely the 

 same specific gravity as those employed by Dr. Bastian. 

 This I was specially careful to do in relation to the 

 experiments described and vouched for, I fear incau- 

 tiously, by Dr. Burdon Sanderson in vol. vii. p. 180 of 

 ' Nature.' It will there be seen that, though failure 

 attended some of his efforts. Dr. Bastian did satisfy 

 Dr. Sanderson that in boiled and hermetically-sealed 

 flasks Bacteria sometimes appear in swarms. With 

 purely liquid infusions I have failed to reproduce this 

 result. Hay- and turnip-infusions, of accurately the 

 same character and strength as those employed on 

 the occasion referred to, were prepared, boiled in an 

 oil-bath, carefully sealed up, and subjected to the 

 proper temperatures. In multiplied experiments they 

 remained uniformly sterile.^ 



' One hundred and twenty flasks, hermetically sealed, contain- 

 ing animal and vegetable infusions, some two, some three years old, 

 are now beside me. They show no sign of Bacterial life. 



