358 On the Diatomacece. [Sess. 



from having visited it, is the Kinord deposit, near Dinnet, in 

 Aberdeenshire. It is several acres in extent, and the diatom- 

 aceous deposit is several feet in thickness, lying under a surface 

 layer of peat moss. To a casual observer the whole appears as 

 if it were ordinary peat, its colour before it is dug out resem- 

 bling that of peat. When it is dug out and dried, it assumes 

 a light-grey colour, and is very light in weight. Some of the 

 best patches of it are pure diatoms " bound together by frag- 

 ments of Sphagnum, Equisetum limosum, E. fluviatile, &c." 



The Eev. Dr Davidson, minister of the parish of Logie- 

 Coldstone, whose manse is near the deposit, has made an 

 exhaustive examination of it, and has identified 200 different 

 species of diatoms. You will find the list of these in a paper 

 by Mr W. Ivison Macadam in the ' Trans. Geol. Soc. Edin.,' 

 vol. iv., part iii., p. 207. Dr Davidson was the first, I 

 believe, to draw attention to the value of this deposit as a 

 commercial article. When it is dug out and dried, it is ex- 

 ceedingly light and porous, and has thus great absorbent 

 capacity. It was thus thought it would take the place of the 

 German " Kieselguhr " in the manufacture of dynamite, and 

 for some years large quantities were taken by Nobel's Ex- 

 plosives Company. Of late years this demand has somewhat 

 slackened, but there is still a small trade in it being done. 



On the occasion of my visit, Dr Davidson drew my atten- 

 tion to an interesting fact bearing upon the nutriment neces- 

 sary for diatoms. Thus on the west side of Loch Kinord a 

 burn falls into the lake, the water of which is charged with 

 silex, and it is here that the diatoms are found in great quan- 

 tities. Close to Loch Kinord there is another lake, Loch 

 Dawin, which is fed by a " stream which takes its rise about five 

 miles distant, on a hill, mostly consisting of hornblende, and in 

 it scarcely any diatoms, either fossil or recent, are to be found." 



Collection. 



Now that you know where diatoms are to be found, your 

 next stage is to collect them. Of course in the case of fossil- 

 beds all that is necessary is to take a sample of the deposit. 

 For the collection of living diatoms, no costly apparatus is 

 necessary. An attentive eye and good judgment are the best 



