1893.] MICROSCOPICAL JOURNAL. 205 



down on the stain where they remain about fifteen minutes; 

 wash in flowing water for a few seconds ; dry between filter pa- 

 per; and mount in Canada Balsam. If the stain has been pro- 

 perly used the red blood cells should have a reddish brown color, 

 all nuclei green, the Eosinophile granules red, and the neutro- 

 phile violet. 



The steps for using Eosine Methyline Blue solution are as 

 follows : 



Fix the pre})aration by heating them on the copper plate for 

 one hour ; place on the stain for 24 hours, care being taken to 

 prevent evaporation ; rinse in flowing water, dry between filter 

 paper, and mount in balsam. All nuclei will be blue, the 

 blood cells red, and the Eosinophile granules red. 



The Bausch & Lomb Opt. Company of Rochester, N. Y., 

 have prepared a considerable quantity of this stain which has 

 been very carefully tested at the Histological laboratory of the 

 Universit}'' of Michigan, giving the most excellent results. It is 

 put up by them and o^itainable in 2 oz. bottles at a very moder- 

 ate price. Full directions for using the stains accompany each 

 bottle. Of them may also be obtained the copper plate with 

 support, as also the cover-glass forceps which is a very desirable 

 accessory , serving a purpose not only for the above, but for 

 other work as well. 



Rochester, N. Y., July 25, 1893. 



Magnetic and Glassy Particles on House-Tops. 

 By K. M. CUNNINGHAM, 



MOBILE, ALA. 



Having taken an interest in the subject of a probable " cosmic 

 dust," as reported by a contributor from Calcutta, India, to ibis 

 Journal (March, 1893, page 72), I am enabled to contribute ad- 

 ditional details relating to the subject. A corroboration of the 

 phenomena observed by him was invited. 



What I have found has all the peculiarities of the dust found 

 on the terraced roofs of houses in Calcutta, and reported to the 

 Calcutta Microscopical Society. And its source of origin is 

 fully explained, I think, in this wise. Wherever mineral coal 

 is burned on a large scale, as in furnaces or locomotives, there 



