548 Adeney — Dissolved Gases and Fermentative Changes. , 



refer for a more complete description of the principles of the apparatus and its 

 applicability to other operations than that here described. 



In this Paper I will only give a short description of the apjDaratus shown in 

 the drawing, sufficient to explain the improvements which has been made on the 

 older form, and to render intelligible the use of the apparatus for the purposes of 

 this research. 



Its essential pai'ts are a gas burette and laboratory vessel, differing in many 

 respects in form and use from those generally employed in other forms of gas- 

 analysis apparatus, and a long pressure-tube provided at its upper end with a 

 Friedrich's patent glass stopcock. 



Tlie form of the burette is exactly similar to that employed in my older 

 apparatus. It is contracted at its lower end, and passed through a hole cut in the 

 centre of the indiarubber bung which closes the lower end of the glass cylinder, 

 enveloping the burette, and which thus provides a means of keeping the burette 

 surrounded with a water-jacket. It is then bent at right angles, and joined to the 

 pressure-tube by indiarubber tubing lined with canvas, and tightly wired to the 

 glass tubes. The bottom of the cylinder, the joint and bent portions of the 

 burette and pressure-tube sit in a trough cut out, and suitably shaped from a 

 piece of solid mahogany, and which, during work, is kept filled with mercury to 

 protect the indiarubber joint from the air. 



The way in which the glass C3dinder, burette and pressure-tube are supported 

 is indicated in the drawing, but this will be more clearly understood from the 

 drawing of the older form of the apparatus. 



The supply of mercury to the burette and pressure-tube is regulated by means 

 of a reservoir, which rests in a wooden box, suspended by a catgut line, and 

 capable of moving freely from the top of the apparatus to the floor. It is 

 prevented from swinging by a grooved guide fixed to the back of the apparatus, 

 in the grooves of which slide corresponding portions of the box. The catgut line 

 passes over the necessary lead pulleys to the windlass mentioned below. 



The reservoir box can be raised or lowered by a small winch or windlass fixed 

 in front of the apparatus, as shown in the drawing, and fixed at any point by the 

 rachet cut on one side of the winch drum. The flexible tube from the reservoir 

 passes through a hole, cut in the wooden upright supporting the apparatus, at a 

 point just below the level of the side branch from the pressure-tube, and is 

 attached thereto. 



It is essential that the flexible tube from the reservoir should be attached to the 

 pressure-tube, and not directly to the burette, because, when the reservoir is kept 

 for any length of time at a lower level than that of the bottom of the burette — 

 and this is constantly necessary when employing the apparatus as a vacuum 

 pump, or when measuring gases under very low pressure — there is a tendency 



