CLEANING AND MOUNTING DIATOMS. 291 



some five or six repetitions we shall find very little but 

 sand in the first bottle ; this we will throw away unless 

 some very large diatoms remain, which can be removed by 

 drying on a slide and picking with a mechanical finger. As 

 soon as the material in the large bottle has settled, turn off 

 the water and return the material to the small bottle and 

 repeat the process, allowing longer time to settle. This 

 process may be repeated five or six times, or as many times 

 as necessary to make the separation satisfactory, allowing 

 more time on each repetition to settle. Another excellent 

 method is used by Christian Febiger, of Wilmington, Del., 

 whose arranged slides have attracted much attention. 

 Strain through No. 18 bolting cloth to obtain large diatoms. 

 The remaining small diatoms and sand must be placed with 

 water in a clock crystal and rotated. The sand will go to 

 the bottom, and the diatoms can be poured off repeatedly 

 until as clean as desired. 



It will be impossible to save all the diatoms in the 

 repeated washings. So long as 100 slides can be mounted 

 from a mass not so large as a small pea, be content to save 

 time and patience by losing a tithe of the harvest. Do not 

 be disappointed when you find hardly enough diatoms 

 remaining to make a fair thickness of carpet in your phial, 

 for if clean you will have sufficient for yourself and for 

 several of your friends, even then. 



For mounting, always place with a pipette a drop of 

 the fluid containing them upon the cover-glass, and never 

 on the slide. Professor Hamilton L. Smith is the author 

 of the following excellent method. Cut a piece of 

 photographer's tintype into strips about I inch wide 

 and 3 inches long, then cut away all except enough for a 

 handle, leaving I inch square on one end ; bend the end of 

 this handle, and fasten into a cork in a bottle, which will 

 serve for a holder. Upon this plate place the clean cover, 



u 2 



