598 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



been in use for a long time, where a jet of air playing across the top 

 of a tube draws up the fluid from its interior by tending to make a 

 vacuum in it. The bellows used are the ordinary hand ones sold for 

 carbolic and other spray-producers, these being as cheap and efficient 

 as any that can be got. In working at the spray points, I began by 

 selecting the size of air-hole that these bellows could easily feed with 

 a continuous blast of air, and then, experimenting with various sizes 

 of vaccine tubes, I found at last, that with the smallest size I could 

 produce a spray which, at about 1-2 in. distance from any object, 

 contained just as much ether as the given blast of air could evaporate. 

 There was then of course no running of the ether to waste, while at 

 the same time an intense cold was very rapidly produced. The 

 method of adapting the spray points to one another is a modification 

 of the ordinary one, and is adopted fi-om a German model. It is as 



Fig. 118. 



follows : — Two fine brass tubes are taken — one is brought to the 

 requisitely fine point for the ether, and the other, being closed at the 

 end, has the air-hole bored at the side a little below the closure. The 

 point of the ether tube is then placed over the middle of the air-hole, 

 and the tubes, laid one over the other, are soldered together in this 

 position ; the free ends of the tubes are then connected with the air 

 bellows and the ether bottle respectively by means of indiarubber 

 tubing, and this part of the apparatus is complete. 



The microtome (fig. 118) consists of the framework, and the 

 mechanism for raising the section. The framework is of 1-2 in. 

 mahogany, and is in the form of a base with two upright parallel 

 pieces screwed on to it. The base A, which is about 2^ by 4 in., 

 is bored to allow the tubes for raising the section to pass up between 

 the parallel pieces, and has a projecting part at one side to allow of 



