1034 RECORD OF CURRENT RESEARCHES RELATING TO 



Cleaning Diatoms with Soap.* — Dr. H. Stolterfoth having tried to 

 clean some of the Welsh deposits hy the common acid process, which 

 gave very poor results, even alkalies destroying the valves of the 

 larger Surirellce before they were free from the dirt, boiled them in 

 soap and water for about an hour, with excellent results. The process 

 is also applicable to all kinds of fresh- and salt-water deposits. 



The method is this : Place in a test-tube (6 inches by 1 inch) a 

 portion of the earth, about ^ inch in depth, and pour in water till the 

 tube is one-fourth full ; into this drop a piece of common yellow 

 soap, about the size of a small pea, and boil gently over a lamp. The 

 solution should be examined under the Microscope from time to time, 

 by taking out a drop with a dipping-tube, and putting it on a slide ; as 

 soon as it is seen that the valves are clean, fill up the test-tube with 

 cold water, and let it stand, then wash in the usual way, until all trace 

 of soap is removed. 



In pouring on the cold water after the boiling, the solution is 

 quite fluid as long as the water is warm. During this time the diatoms 

 fall to the bottom, but, on getting cold, the solution assumes a some- 

 what jelly-like consistency, and holds the fine particles and mud in 

 suspension, and is a very useful means of getting rid of what is often 

 a great trouble. 



In deposits in which there is much organic matter, recourse must 

 still be had to acids or fire to destroy this, but the result will be im- 

 proved by afterwards boiling in soap and water. The author has also 

 boiled fresh gatherings in soap and water, and then burnt on platinum 

 foil with good success, much of the flocculent matter being removed. 



Dr. E. Kaiser, of Berlin, referring to this paper, says t that the pro- 

 cess was communicated to him several years ago from England, but 

 that " it has very many defects and inconveniences." 



Separation of Heavy Microsopic Minerals.;}: — In order to separate 

 minute particles of heavy minerals, of diiferent specific gravities, from 

 each other, M. Eene Breon proposes to employ a mixture of the fused 

 chlorides of lead and zinc, the respective specific gravities of these 

 two liquids being 5 and 2*4, so that by properly proportioning the 

 mixture, any two minerals of different specific gravities, but lying 

 within the above limits, can be separated. The fine powder to be 

 experimented on is thrown into the fused chlorides contained in a 

 conical glass tube, when the particles speedily come to rest, some 

 floating, and the others sunk at the bottom of the tube ; the mass is 

 then allowed to cool, and when set, the tube is plunged into cold water, 

 thus cracking the glass. The upper and lower portions of the mass 

 of chlorides containing the minerals can then be removed, and the 

 chlorides dissolved out with water acidulated with hydrochloric acid. 



Pearson-Teesdale Microtome. — At the October Meeting Mr. 

 Washington Teesdale exhibited a small and convenient form of micro- 



* ' Journ. Quek. Micr. Club,' v. (1880) pp. 95-6. 

 t ' Bot. Ceiitralbl.,' i. (1880) p. 1213. 



% ' Bull. Soc. Min. France,' iii. See ' Mineralog. Mag. and Journ. Mineralog. 

 Soc.,' iv. (1880) p. 129. 



