180 Dr. G. Child on the Production of [Apr. 27, 



holder, and bubbles through the' sulphuric acid at the other end. The 

 substance in the bulb is then boiled for ten or fifteen minutes, the lamp 

 withdrawn, and the bulb allowed to cool while the stream of air is still 

 passing through the porcelain tube, maintained during the whole time at 

 a vivid red heat. When the bulb is quite cool, the necks are sealed by 

 means of a lamp. The advantage gained by means of this apparatus is 

 that there is only one joint the perfection of which in any degree affects 

 the success of the experiment, and of that joint it is easy to make sure. 

 The porcelain tube also being, for a considerable part of its length, filled with 

 small fragments of porcelain, all heated up to redness, easily ensures that 

 every particle of air admitted to the bulb shall be thoroughly heated. A 

 precisely similar arrangement was used for the nitrogen experiments, sub- 

 stituting a glass combustion-tube filled with copper-turnings for the porce- 

 lain tube, and a piece of india-rubber tubing for the india-rubber cork. 

 The copper oxide was reduced by means of a stream of hydrogen when 

 necessary between one experiment and the next. 



A single experiment was tried on May 18, 1864, using apparatus similar 

 to that employed in the experiments of the previous year. 



Some pea-meal infused in water was boiled in a stream of heated air, 

 allowed to cool, and then sealed and put by. I was then prevented from 

 resuming my experiments for several weeks. 



Then several experiments were made with nitrogen, for the purpose of 

 confirming or correcting the nitrogen experiment of the previous year. 

 Into the particulars of these I need not now enter, further than to say 

 that seven experiments were tried with various infusions. Five of them 

 were afterwards examined, and in no case were any organisms found, thus 

 confirming me in the opinion already expressed upon that experiment. 

 The series with which I am now concerned began on July 18. 



VII. July 18. Hay infused in water three hours, then filtered and boiled 



12 minutes in a stream of heated air, and sealed up as above de- 

 scribed. 



VIII. July 18. A similar experiment : boiled 10^ minutes. 



IX. July 22. Toppings, i. e. coarse flour infused in cold water 3 hours, 



filtered and boiled 10 minutes in a similar stream of air. 



X. July 22. A similar experiment: boiled also 10 minutes. 

 XL July 25. A similar experiment: boiled 12 minutes. 



XII. July 25. A similar experiment: boiled 10 minutes. 



XIII. July 28. Some sage-leaves bruised and infused in lukewarm water 

 previously boiled. Allowed to stand 15 hours, filtered, and the 

 clear fluid boiled 10 minutes in a stream of heated air, as in the 

 other cases, and sealed up. 



XIV. July 28. A similar experiment : boiled 7 minutes. 



XV. July 29. A similar infusion of celery, allowed to stand 12^ hours, 



and treated as the last : boiled 12 minutes. 

 The bulb used in this last experiment was of a different form, which I 





