38 DIATOM \< 



ence, the following-named articles are recommended as neces- 

 sary for the work of cleaning and isolating Diatoms, which 

 should be done in a chamber high above the ground, if possi- 

 ble, and not heated in winter by a flue. Hot-water pipes are 

 far better, as affording immunity against dust. We enumerate: 



German beaker glasses of different sizes, with a number of 

 small china plates to serve as covers; several large watch- 

 glasses, or shallow glass capsules of like shape; solid glass 

 rods for stirring; small glass tubes or pipettes; a sand bath and 

 an apparatus for heating: nitric acid, chlorhydric acid, sul- 

 phuric acid, — all the best " commercial," except the last, which 

 should be " C. P. ;" carbonate of soda and carbonate of potassa, 

 both C. P.; Atkinson's alcohol; freshly distilled water, and a 

 copious supply of filtered soft water. 



For displaying a cleaned sediment with a view of securing 

 individual specimens, a number of glass slides one and a half 

 inches by four inches should be provided; and for the preserva- 

 tion of finished work, or clean Diatoms, a score of small 

 bottles, with corks already fitted. 



Finally, a large camel's-hair pencil; a few slender cane (reed) 

 strips, to serve eventually, when pointed very finely, to pick 

 out single valves; a supply of litmus paper; a glass funnel, and 

 Saxony filter paper, complete the category. 



Method to be Employed. As pure Diatoms, guano findings, 

 and diatomaceous earths or clays each require separate modes 

 of treatment, let us first handle a guano specimen, because 

 some of the steps to be trodden may be called fundamental, or 

 we may say they are of very general application: still, they 

 must in certain instances be preluded by others, may not be 

 wholly needed in particular cases, and are of necessity to be 

 followed by supplementary processes demanded by the peculiar 

 nature of the products obtained. 



A guano, such as the Chincha or that of Ichaboe, ought to 

 be coarsely sifted to free it from pebbles, feathers, and masses 

 of crystallized substances. The better part is still, how T ever, 

 very heterogeneous, consisting of Diatoms in a very small per- 

 centage, and of much extraneous matter, earthy, salty, and 

 excrementitial. Boiling water dissolves a great part of all 

 these, and should be repeatedly applied to the deposit, and as 



