172 



SCIENCE-GOSSIP. 



Eliya. No mention whatever is made of any 

 armature, and the systematic position of the 



Fig. gz.—Kaliella (?) eugcvii (after Jousseaume). 



species, therefore, remains doubtful ; if it really 

 be a PlectopyJis it will in all probability be 



found to belong to the section Sykesia. Mr. Sykes 

 has doubtfully suggested (Proc. Malac. Soc. 

 London, iii. (1S9S), p. 71) that it belongs to the 

 genus Sitala ; but I do not think this is probable. 

 In the same work (p. 277, t. 4, f. 1) Dr. Jousseaume 

 described another shell which he also places in 

 Plectopylis, i.e. P. eugenii. In this case also no 

 mention is made of armature ; moreover, the figure 

 given, which I have copied for convenient reference 

 (see fig. 92), does not at all give the idea of a 

 Plectopylis, and I agree with Mr. Sykes in thinking 

 that it may belong to the genus Kaliella. 



Note. — By an oversight fig. 78/ on page 74 has 

 been placed upside down. 



{To be continued.) 



PREPARATION OF DIATOMACEOUS MATERIALS. 

 By Edward H. Robertson. 



XJOTWITHSTANDING all that has been 

 ■^ written on the preparation of diatomaceous 

 materials for microscopic purposes, it is surprising 

 how few amateurs can deal with these materials 

 in anything like a satisfactory manner. My pre- 

 sent object is to give a brief outline of the methods 

 I have myself practised for half a century, and 

 with almost unvarying success. The following 

 are a few of the indispensables required, both in 

 the matter of apparatus and chemicals ; they are 

 mostly inexpensive. One Wedgwood pan, or 

 pipkin, furnished with lid and handle (ordinary 

 shallow evaporating pans are utterly useless for 

 the preparation of micro-material) ; two or 

 three glass beakers of about half-a-pint capacity 

 each ; a few test tubes ; sundry common tumblers, 

 or old-fashioned ale-glasses ; three or four stop- 

 pered bottles, each of about one-pint capacity ; 

 a few glass slips ; and two or three glass rods, 

 from six to eight inches long, tapering to a 

 point, and about the thickness of a common pen- 

 holder. Of chemicals the following are absolutely 

 requisite, viz : 1 lb. of common hydrochloric acid, 

 at 3d. per lb.; 1 lb. of common sulphuric acid, at 

 4d. per lb. ; 1 lb. of common nitric acid, at Sd. per 

 lb. ; 1 or more ounces of chlorate of potash, at 

 2d. per ounce ; a similar quantity of bichromate of 

 potash, at i^d. per ounce: 7 or S lbs. of carbonate 

 of soda, at Gd. per 12 lbs. ; half-a-pint of liquor 

 potassa (Brandish's solution), at is. per lb.; 

 sundry quarts of distilled — not simply filtered — 

 water, at 4d. per gallon ; and the same quantity of 

 pure rain water. 



So much for the outfit of the amateur diatomist. 

 Thus furnished he may safely tackle all but the 

 most refractory materials with the certainty of 

 a favourable result, always provided that he has 

 an unlimited stock of patience. If this excellent 



quality be not his happy possession, then let him 

 leave the manipulation of diatomaceous materials 

 to those whose it is, and himself purchase slides 

 of diatoms from some of the many first-class 

 dealers in these objects, and — lose half the pleasure 

 of filling his cabinet with his own mounts. If 

 economy be a consideration, and he fertile in 

 resource, the reader will be able to substitute 

 even less costly apparatus for that indicated. It 

 is astonishing what a large amount of useful work 

 may be accomplished with the most unpromising 

 appliances. When, a mere lad, I commenced the 

 preparation of microscopic materials — the subject 

 of this paper — my sole outfit was a common 

 gallipot, a glass rod, and a few ounces of 

 nitric acid ; my laboratory the hobs of the 

 sitting-room stove — to the great distress of the 

 good housewife and the detriment of the fireplace 

 and its appurtenances. Yet with these rude 

 appliances I successfully prepared very refractory 

 guanos, etc. I have, however, long since learned 

 that work may be done with infinitely more com- 

 fort with proper though; perhaps, more expensive 

 apparatus. 



Fossil Materials. 



From whatever source obtained, 'fossil diatoma- 

 ceous materials are almost invariably received by 

 the operator in the form of lumps of rock or 

 earth. Some, for instance the Nottingham, U.S., 

 materials, are almost chalky in consistence, others, 

 as that from Sendai, Japan, are of stony hardness. 

 Hard or soft matters not, the first process must 

 be their reduction to an impalpable powder. This 

 must on no account be done by pounding or 

 breaking with a hammer, which would simply 

 mean the utter destruction of all the finer forms 

 contained therein. Their disintegration may be 



