95 



On a Simple Method of Cleaning Diatoms. 



By Dr. H. Stolterfoth, M.A., 



Scientific Secretary of the Chester Society of Natural Science. 

 {Read Aijril 2Zrd, 1880.) 



In bringing before your Club my new process of cleaning, I do 

 not pretend that it is universally applicable, but I have found it so 

 useful, and many of my friends have used it with such good results, 

 that I wish to make it more generally known. I was led to it by 

 trying to clean some of the Welsh deposits. Very poor results 

 were obtained by the common acid process, and even alkalies de- 

 stroyed the valves of the larger Surirellce (in which these deposits 

 abound), before they were free from the dirt with which they were 

 filled. I then thought that it was thorough washing these forms 

 required, and what would answer better for the purpose than Soap? 

 — so I boiled them in soap and water for about an hour, and I was 

 quite astonished at the result. Since then I have tried the process 

 on all kinds of fresh and salt-water deposits, and should now never 

 think of returning to the old process, with its spirting acids and 

 alkalies which so often injure the valves. 



The method I follow is this : I place in a test-tube (Bin. long by 

 lin. wide) a portion of the earth or mud about ^in. in depth, and 

 pour in water till the tube is :|th full ; into this I drop a piece of 

 common yellow soap, about the size of a small pea, and then boil 

 gently over a lamp. I examine the solution under the microscope 

 from time to time, by taking out a drop with a dip-tube, and putting 

 it on a slide ; as soon as I see that the valves are clean, I 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, and then mount in any 

 way you please. 



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 somewhat jelly-like consistency, and holds the fine particles and 



JouRN. Q. M. C, No. 44. i 



