ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



157 



Fig. 37. 



larger tube is closed with a cork bung, through which pass two tubes. 

 One of these is Y-shaped, and has at its lower extremity a small bag 

 made of vegetable parchment. The arms of the Y are connected by 

 means of a cross tube having a narrow lumen, and the ends of the arms 

 are joined on to a caoutchouc tube through which the gas passes. The 

 effect of this arrangement is that when the water gets hot, the mercury 

 with which the leg and bag of the Y-shaped tube are filled, rises into 

 the Yj and thus shuts off the gas. The stream of gas, however, is still 

 kept up through the narrow connecting tube, and this prevents the light 

 from going out altogether. The second glass tube has a funnel con- 

 nected by means of a short piece of rubber tubing and forms the arrange- 

 ment whereby the apparatus is regulated for a given temperature. For 

 when the water begins to get j_warm it rises up the tube and so into the 

 funnel, the mercury remaining stationary. Directly the desired tem- 

 perature is reached, a strong clamp is put on the short piece of rubber 

 tubing, and then the mercury begins to regulate the supply of gas for 

 this temperature. If a higher temperature be desired, it is only 

 necessary to remove the clamp and allow the water to ascend until the 

 proper point is reached, and 

 then re-clamp. If a lower 

 one be necessary the clamp 

 is undone, and the gas-jet 

 removed until the tem- 

 perature has fallen. 



Stein's Steam Funnel.* 

 — Dr. L. V. Stein has con- 

 structed a funnel for facili- 

 tating the filtration of 

 gelatin and agar solutions. 



The outer funnel A, 

 fig. 37, is made of copper, 

 and has the following di- 

 mensions : — Diameter, 14 

 cm. ; height 10 cm, ; sides 

 A B, 6-7 cm. The tube 

 for heating it C, is seen at 

 one side. The internal 

 filter D has sides 3 cm. 

 high, its diameter is 9 cm., 

 and its height 10 cm. It 

 is covered with the lid B, 

 into which are soldered the 



two tubes E and F, both being closed with corks. The filter is filled 

 with water through E, and through F passes the solution to be filtered. 

 In the middle is seen the section of the glass funnel G, the stem of 

 which is fixed tight by the cork bung H. 



When required for use, the copper funnel is filled with water as far 

 as A, and a filter-paper placed within the glass funnel. As the steam 

 developes it exerts some pressure on the fluid, since it can only escape 

 through the stem of the glass funnel. In one hour 100 cm. of a thick 



Zeitschr. f. Wiss. Mikr., v. (1888) pp. 329-30 (1 fig.). 



