29 



It may be noted here that carborundum is a very handy grind- 

 ing material. It is harder than emery and cuts more quickly and 

 may be obtained in any grade of powder from the manufacturers 

 at the electrical works at Niagara Falls. The writer has pre- 

 pared ground-glass plates of consider- 

 able size and has ground covers to dishes, 

 joints in tubes, etc., with a minimum 

 amount of trouble by means of this car- 

 borundum. 



But to return to the respiration appar- 

 atus. The test-tube having been ground 

 into the neck in a satisfactory manner, 

 its end is next blown out, by heating and 

 blowing while in a Bunsen flame. The 

 hole thus produced may be easily en- 

 larged to any size by moulding with a 

 piece of cold metal. 



The tube should now be graduated, 

 which may be done by corking up the 

 end of the tube and running in water 

 from a burette, marking on a paper scale 

 glued to the side any graduation — I or 

 5 cc. — that is desired. For use, the flask 

 is filled with seedlings, flowers, leaves, or 

 whatever is to be investigated, and a plug 

 of cotton, loosely poked in, to prevent 

 their falling out when the flask is in- 

 verted. The extension of the neck is 

 now put with its end (what as a test-tube 

 was its mouth) over mercury. Some 

 strong potash — say 50 per cent. — is run 

 in at the top ; the weight of the mercury 

 will be enough to prevent as much, at 

 least, as 5 cc. from running out. The ground joint of the 

 test-tube is now painted liberally with vaseline, or better vaseline 

 and wax, and the correspondingly ground flask joined to it. The 

 whole apparatus is supported by a clamp on a retort-stand over 

 the dish of mercury. 





^SSMMS^SSa& 



Diagram of Section. The 

 apparatus is supported by a 

 clamp to a retort- stand. The 

 flask is the receiver for flow- 

 ers, seeds, etc. The tube 

 may be graduated or the re- 

 sults may be read simply by 

 comparison. 



