The spoon was so balanced that when nearly full it tilted, the watei 

 was emptied out into a beaker below, and the spoon returned to its 

 original position. As the spoon tilted it momentarily completed an 

 electric circuit. In each of these circuits was an electro-magnet, to 

 the armature of which a pen was attached. The pens (six in number) 

 recorded on a long horizontal drum making one revolution in twenty- 

 four hours. Under ordinary circumstances the pens would rule straight 

 lines on the chart, but when the apparatus was working the trace 

 was somewhat like Figure 2, which is a reproduction of an actual 

 record. This record is easily translated into a curve such as is shown 

 in Figure 1 . Each time the spoon is emptied the pen is drawn aside, the 

 number of dashes shows how many times the spoon was tilted and 

 the quantity of water collected in the beaker indicates the volume of 

 gas evolved. In two tests of the same flour the following results 

 were obtained. In the first the spoon was upset sixty-three times 

 and 392 cubic centimetres and of water were collected ; in the second 

 experiment the spoon was filled and emptied sixty-four times and 

 394 cubic centimetres of water collected. This will serve to show 

 that the arrangement is reliable. 



The general arrangement of the apparatus is shown in Plate I. 

 In the figure, the flask containing the mixture of flour, water, and 

 yeast are shown in the water bath at A ; the flasks B contain water 

 which is displaced by the gas. The water falls into the tipping spoons 

 C and from them into the beakers D placed below. The arrangements 

 of the pens and recording drum is a simple matter and requires no 

 explanation. In the apparatus employed the clock attached to the 

 recording drum caused the drum to revolve once every half-hour. 

 This was useless for the purpose, and in consequence an auxiliary clock 

 was employed having the hands removed and 'the hour hand replaced 

 by a pulley of half the diameter of the revolving drum. A thread 

 was wound round this pulley, then round the recording drum, and 

 finally passed over a small pulley suspended above the drum; a small 

 weight was attached to the free end. The thread was so wound that 

 as the clock caused the pulley to revolve so the thread unwound and 

 the weight slowly descended. The falling of the weight caused the 

 recording drum to revolve, the clock simply serving to regulate the 

 speed at which the weight descended. The drum was thus made to 



