ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



119 



For experiments on the influence of pressure on physical and 

 chemical combinations the substance to be examined should be in- 

 closed in a very long spiral capillary tube, nearly filled with an 



Fig. 5. 



Fig. 6. 



indifferent fluid which on being warmed will exert considerable 

 pressure. By using liquefied gases the effect of low temperatures can 

 also be observed. 



ftueen & Co.'s Class Microscope.* — This (fig. 7) is identical 

 with Waechter's or Engell's instrument already described.! We have 

 had one of the original forms in use for some time, and have found 



Fig. 7. 



it very convenient for exhibiting objects. By daylight it is simply 

 turned to the sky, and there is no difficulty in at once getting the 

 proper illumination. By artificial light the instrument requires some- 

 what more adjustment, unless there is a large illuminating surface or 

 the Microscope is brought close to the source of light. 



Swift-Wale Microscope. — Messrs. Swift and Son have made fur- 

 ther modifications in Wale's model, which is now constructed as shown 

 in fig. 8. The original form was figured in Vol. I. (1881) p. 296. 



* Micr. Bulletin, i. (1884) p. 47 (1 fig.), 

 t See this Journal, ii. (1882) p. 398. 



