1878.] On Intercepting Germinal Matter of the Air. 



m 



for hours by carefully applying interrupted currents to the sinus 

 venoms; and although the authors of this paper, in repeating the 

 experiment, have sometimes failed to inhibit indefinitely — as did also 

 Meyer — they have always found it possible to stop the heart for very 

 long intervals by stimulating the sinus venosus ; even with weaker 

 currents than had just before sufficed to exhaust simultaneously the 

 inhibiting powers of both Vagi. 



II. " On Schulze's Mode of Intercepting the Germinal Matter 

 of the Air." By John Tyndall, F.R.S., Professor of 

 Natural Philosophy in the Royal Institution. Received 

 December 17, 1877. 



In " Poggendorf's Annalen " for 1836, Franz Schulze described an 

 experiment which has attained considerable celebrity. He placed in a 

 flask a mixture of vegetable and animal matters and water ; through 

 the cork of the flask two glass tubes passed air-tight, each being bent 

 at a right angle above the cork. He boiled the infusion ; and while 

 steam issued from the two glass tubes, he attached to each of them a 

 group of Liebig's bulbs, one group being filled with solution of caustic 

 potash, and the other with concentrated sulphuric acid. Applying 

 his mouth on the potash side, he sucked air daily through the sul- 

 phuric acid into the flask. But, though the process was continued 

 from the end of May till the beginning of August, no life appeared. 



In this experiment, the germs diffused in the atmosphere are sup- 

 posed to have been destroyed by the sulphuric acid, and doubtless this 

 was the case. Other experimenters, however, in repeating the experi- 

 ment of Schulze, have failed to obtain his results. The experiments 

 of Dr. Hughes Bennett are a case in point, to which I might add 

 certain failures of my own. Schulze's success is, perhaps, in part to 

 be ascribed to the purity of the air in which he worked ; possibly, 

 also, to extreme care in drawing the air into his flask ; or, it may be, 

 that the peculiar disposition of his experiment favoured him. Within 

 the flask, as shown by his diagram, both his glass tubes terminated 

 immediately under the cork, so that the air, entering by the one tube, 

 was immediately sucked into the other, thus failing to mix completely 

 with the general air of the flask. 



At a very moderate rate of transfer, 1 found, in 1869, that germs 

 could pass unscathed through caustic potash and sulphuric acid in 

 succession. To render the experiment secure, the air-bubbles must 

 pass so slowly through the sulphuric acid, that the floating matter, up 

 to the very core of every bubble, must come into contact with the 

 surrounding liquid. It must, of course, touch the acid before it can 

 be destroyed. 



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