ï)8 



We doubted about the exaetness of' the method with desiccators, we 

 made experiments in another way. We let a piece of gelatine swell 

 under water until the equilil)riuui was attained, put it into a Ü- 

 tnbe with groujid stopcocks, hung this tube in a thermostat, and 

 sucked a stream of air saturated with watervapour through it. In 

 order to fully saturate the air with watervapour, we let it pass 

 in extremely tine bul)bles through four tn.bes of water which were 

 also hanging in the thermostat. We made sure of the vapour really 

 being saturated by placing a U-tube tilled with water before the 

 U-tube with gelatine, and by also weighing the former before and 

 after the air had been led throuo-h. 



TABLE I. 



Time 



Weight of U-tube 



+ water 



Weight of U-tube 

 -|- gelatine 



24 hours 

 26 „ 

 18 „ 



72 .. 



30.130 

 30.127 

 30.126 

 30.123 

 30.117 



30.779 

 30.781 

 30.779 

 30.778 

 30.780 



Temp. 19°. 

 (in thermostat) 



It will lie seen, that the gelatine, coiitrary to our former experi- 

 ments, showed no decrease of weight : it was in equilibrium and it 

 remained so, and there was not the slightest abnormality. Now 

 which method, the old or the new one, is more reliable? The 

 answer cannot be dubious, for we succeeded in improving the old 

 method to such an extent that it gives the same results as the 

 new one. 



Formerly we used to place little dishes of gelatine in a Scheibi.p^r- 

 desiccator, at the bottom of which was some water, and which 

 stood in a room of a fairly constant temperature. In order to exclude 

 the possibility that the water from the gelatine, under the influence 

 of gravity, should distill to the water at the bottom, we have now, 

 instead of pouring the water into the desiccator, placed a dish of 

 water at the same level as that with gelatine. And, thinking of 

 Foote's experiments mentioned in our first communication, we also 

 weighed this dish, expecting, of course, that the water lost by the 

 gelatine, should be found back here. However it appeared that 

 both gelatine and water equally decreased in weight; (it is to be 

 noticed that the desiccator was not evacuated). 



