1893.] MICROSCOriCAL JOURNAL. 205 



down on the stain where they remain about fifteen injnuteH; 

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

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

 j)erly used the red blood cells siiould have a reddish brown color, 

 all nuclei green, the Eosino{)hile granules red, and the neutro- 

 phile violet. 



The step.s for using Eosine Methyline Blue solution arc as 

 follows : 



Fix the jtreparation b^- heating tliem on the copjter i)late for 

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

 prevent evaporiUion ; rinse in flowing water, dry between filter 

 )»aper, and mount in balsam. All nuclei will be blue, the 

 blood cells red, and the Eosinophile granules red. 



The Bausch & Loml) 0])t. Com})any of Rochester, N. Y., 

 have j)repared a considerable quantity of this stain which has 

 been very carefully tested at the Histological laboratory of the 

 University of Michigan, giving the most excellent results. It is 

 put up by them and o^»tainable 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 jjlate with 

 su])port, as also the cover-gla.ss forceps which is a very desirable 

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

 other w'ork as well. 



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



Magnetic and Glassy Particles on House-Tops. 

 By K. M. CUNNINGHAM, 



MOBILK, .\LA. 



Having taken an interest in the subject of a i)robable " cosmic 

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

 JouHXAL (March, 1893, page 72), I am enabled to contributead- 

 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 Microsco])ical Society. And its source of origin is 

 fully explained, I think, in this w-ise. Wherever mineral coal 

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



