1896 THE MICKOSCOPE. 29 



The Microscope in Chemistry. — The value of micro- 

 chemical analysis, and the simplicity of its processes, commend 

 this department of microscopy to general favor. 



A large proportion of the actions and changes produced by 

 reagents may be observed as satisfactorily in drops as in larger 

 quantities. 



Great care should be observed when examining chemicals 

 with the microscope. An objective with a gold front will be 

 found servicable. 



Some Points on Crystal Slides. — The methods of pro- 

 ducing these slides should be varied with the different sub- 

 stances and the different effects desired. 



Sulphate of iron dried on a slide will produce arborescent 

 and fern-like crystals but if stirred with a glass rod or needle 

 while evaporating will form separate rhombic prisms. 



Pyrogallic acid crystallizes in long needles, but a little dust 

 as a nucleus brings about a change of arrangement resembling 

 the " eye " of a peacock's tail. 



A saturated solution dropped into alcohol, if the salt is in- 

 soluble in alcohol, will produce instantaneous crystals. Some 

 substances as salicin will produce bests results by being fused 

 in a slide over a lamp and spread evenly. This may be done 

 with a hot needle. 



SCIENCE-GOSSIP. 



The Micro-organism of Measles. — Joseph Czajkowski 

 (Centralbl. fur Bakt. und Purasit., 18U5, No. 17-18, p. 511) 

 contributes a further addition to our knowedge of the bacillus 

 which he previously described as existing in the blood in mea- 

 sles. The bacilli in the blood vary in length from one-half 

 microraillimeter to the diameter of a red blood-corpuscle, and 

 in cultures grow into long threads. Thsy stain well with all the 

 anilin dyes, and in the longer forms a part of the jDrotoplasm often 

 remains unstained. They loose their stain by Gram's method. 



