37S PNEUMATIC APPARATUS. 



length of these plates together should exceed that of the 

 under plate about an inch. It is rather better to grind the 

 polish oft" the plates with a little fine emery, as they slide 

 more cfjuably over each other when so prepared. All the 

 jars to be used with them should have their mouths ground 

 on a fiat plate with fine emery. Things being thus pre- 

 pared, the transferring plates may be used in the following 

 manner, particalaily when the jars for collecting the gasses 

 are large. 

 Improved ap- When the jars, inverted in the usual manner in the pnei;- 

 transferring Hiatic trough, are filled with the gas in any proportion, the 

 the gasses. two plates (a and h) are laid over each other in such a situa- 

 tion,tl.at their holes shall not coincide ; th<^y are then plunged 

 into the water, and the plate (q) applied to the mouth of 

 the jar^ and that and the plate (I) being moderately pressed 

 against the mouth, so that they shall not slip, or suft'er any 

 g"as to escape, th-e jar together with the plates, is lifted out 

 of the water, and set with the mouth turned up. In Uiis 

 position the jar is ready for yielding the gas to the jar into 

 which it is to be transferred. This last jar is now to be 

 filled with water, taking care not to leave any air in it, and 

 its mouth Is to be closed by the third plate. It is then tq 

 be tyrned with its mouth downwards, and, toget|xer with the 

 third plate on which it stands, is to he placed on that part 

 of the under plate which is not covered by the upper plate. 

 The edges of the third and upper plate are placed as nearly 

 as possible in contact 5 and across them the sntall jar, filled 

 with water, is to be slided till it rests entirely on the upper 

 plate. The hole in the upper plate is to be filled with a 

 few drops of water, and the jar is to be slided so as to stand 

 over it. The upper plate, and the jar standing upon it,a.ie 

 then to be so moved over the under plate, that the holes 

 in each shall coincide. The water in the upper jar, as soon 

 as the communication is thus opened, will descend into the 

 Jower or magazine jar, and be supplied with an equal bulk 

 of gas from below at pleasure. When a sufficient quantity 

 is transferred thus into the upper jar, it is pushed together 

 with its plate, in such a manner that the holes shall no longer 

 coincide, and, consequently, the communication shall be cut 

 pff, The upper jar ii elided back upon the third plate, 



and. 



