1894.] MICROSCOPICAL JOURNAL. 217 



imens. — C. A. Oliver in the International Medical Magazine, 

 February, 1994, described an air-tight cell for the preservation 

 of microscopic eye-specimens. It is made of two parts, the 

 upper one being of glass in the shape of a petry, or chemical 

 crystallizing dish, which sets in a celluloid base by means of a 

 deep circular groove. The glass is filled with the preservative 

 ■fluid (gelatine), the specimen introduced and the base applied, 

 and the whole inverted, the raised bottom will press out all air 

 bubbles and the glass can then be cemented to the base. A 

 single hand magnifying glass of any amplification or the ordin- 

 ary dissecting microscope is then used for examining the speci- 

 men. 



The Jena Glasses. — The researches of Abbe and Schott at 

 Jena, have resulted during the past 10 years in the production 

 of several improved grades of optical glass, and especially the 

 pairs of flint and crown glass in which the dispersion in various 

 parts of the spectrum is much more nearly proportional. By 

 the use of these glasses the magnitude of the secondary spectrum 

 is greatly diminished. A combination of a heavy barium- 

 phosphate-crown glass is made with a borate-flint glass in 

 which the focus differences range between — 0.04 and 0.79. 



Erector for a Microscope. — In an ordinary terrtstial tele- 

 scope, the eye-piece consists of four lenses — two next the eye, 

 which form a Huyghenian eye-piece, and two at a little distance 

 from them, which perform the duty of reversing the image and 

 enabling us to see it in its proper position. These two lenses 

 will form an efficient erector for the microscope, or the whole 

 four-lens eye-piece of the telescope may be used as an erecting 

 eye-piece instead of the ordinary Huyghenian. — Dr. Blacklock in 

 The Eng. Mech. 



MICROSCOPICAL MANIPULATION. 



Soldering Glass to Metal. — The piece of glass is first cov- 

 ered with a thin layer of platinum. This deposit is secured by 

 brushing over the slightly heated glass a natural chloride of 

 platinum mixed with essential oil of chamomile. The latter is 

 slowly evaporated and when the white and odoriferous vapors 

 have ceased, the temperature is raised to a red beat which 



