PROCEEDINGS OP SOCIETIES. 145 



the diatoms on the paper disc may be removed by a camel-hair 

 pencil or otherwise, ready for mounting. Thus many objects may 

 be preserved which would be either washed away or only be avail- 

 able by a more tedious process. 



Mr. J. B. Dancer, F.E.A.S., "On Cleaning and Preparing 

 Diatoms, &c., obtained from Soundings." — The first operation 

 generally required is to separate the soundings from the tallow 

 or fatty matter which has been employed to bring them up 

 from the bottom. 1 may here mention that Lieutenant Stell- 

 wagen, an American officer, has invented a sounding-lead which 

 does not require grease. It has a trap at the bottom for col- 

 lecting the soundings. I am sure our section will join with me 

 in the wish that the soundings which our worthy Secretary 

 hopes to receive from various parts of the world may be collected 

 with an apparatus of this kind. The grease involves a considerable 

 amount of trouble, and some loss. The mass of soundings and 

 grease is to be placed in a basin or an evaporating-dish, and boiling 

 water poured on it ; the melted fat rises to the surface, and when 

 cold can be easily skimmed off. This operation may be repeated 

 until the sediment appears free from grease ; to insure this, draw 

 the water carefully from the sediment, and pour liquor ammonia on 

 it ; I prefer it to potass or soda ; this will combine with the grease, 

 if any remain, and form a soapy solution. This may now be 

 treated with hot water for the final washing. The sediment must 

 be allowed to settle quietly for an hour or two each time before the 

 water is carefully decanted or drawn off with a syphon; otherwise 

 the minute forms of Diatomacese will be lost, and the operator 

 greatly disappointed in the result of his labour. Having now 

 cleared the soundings from all extraneous matter, the next opera- 

 tion is to ascertain, by the microscope, the nature of the objects 

 thus obtained. Take up with a glass tube some of the sediment, 

 draw the contents of the tube along a slip of glass, and examine it 

 with a low power. If Foraminiferse or large Diatomacese are pre- 

 sent, they maybe removed by means of a split hair or a bristle from 

 a shaving-brush, gummed or fixed in a cleft in a slip of wood, and 

 then placed on a clean slip of glass for further examination. If you 

 have a considerable quantity of mud or sand under the operation, 

 with an abundance of Foraminiferse, as is frequently the case, they 

 can be separated by first drying the soundings, and scattering them 

 on the surface of water in a basin ; the heavy particles of sand will 

 sink, but the light Foraminiferse will float for a time, and can be 

 easily collected. Another mode is to stir up the sediment, and 

 then pour off the lighter articles into test-tubes or wine-glasses. In 

 this manner, by having a number of glasses, you can separate the 

 varieties according to their specific gravities. If the Diatomacese 

 obtained are recent and abundant, they should be separated from 

 the calcareous portions of the soundings, and boiled in hydrochloric 

 acid ; and if not sufficiently cleaned, they may be boiled in nitric 

 acid. The contents of the diatoms can be removed by burning 



VOL. I. — NEW SER. L 



