OF THE DIATOME^. 107 



matter from entering the gas-pipe. Ha\dng thus reached the bottom of the 

 hole, now pull up the cork into the gas-pipe about 4 feet, by means of the 

 rod attached to it, and then j)^^ss the whole apparatus into the soft mud. 

 The pressure will now diive the mud up into the pipe as far as the cork is 

 di'awn up. Now remove the whole apparatus, and by means of the rod push 

 the cork back again to the end of the last length of pipe, when the charge of 

 mud -^ill be driven out in the form of a sausage ; and by rejecting the two 

 ends of it, and taking only the middle piece, we may be perfectly sure that 

 the mud at that depth, and that only, has been obtained. 



" Ha\dng secured the prize, the short length of piping which contained it 

 is now to be unscrewed, and carefully washed ^vith a common gun- cleaning 

 rod and some tow, when it is ready for another experiment. 



" With this apparatus, then, I have penetrated Neyland mud in various 

 places to depths of 20, 30, and 40 feet." 



The Diatomeae existing often so abimdantly in Guano may be separated on 

 a simpler plan to that pui^sued in the case of sedimentary deposits and col- 

 lections of fossil specimens. The proceeding is always preceded by several 

 washings in clear water, and by pouring it off carefully, after allowing 

 a sufficient time for the insoluble and more weighty particles to subside. 

 The subsided matter is then treated with hydrochloric (muriatic) acid several 

 times, — a due inter\' al being allowed for the cessation of effervescence and 

 for the solid particles to settle before the decanting of the liquid and the ap- 

 plication of a fresh quantity. A\Tien the muriatic acid ceases to produce any 

 chemical action, as evidenced by effervescence, nitric acid should be substi- 

 tuted and used in a similar way two or three times, and the mixture raised 

 to nearly or quite a boiling heat, after which the powder collected at the 

 bottom of the vessel — a conical one should, by the way, be preferred, such as 

 chemists know by the name of " precipitate glasses " — is to be washed re- 

 peatedly in pure water. The resultant substance will be found to be com- 

 posed of silicious particles, which are either Diatomaceous frustules or the 

 silicious spicules of Sponges. 



Prof. Bailey, in a recent number of SilUman^s Journal, 1856 (p. 145), re- 

 commends the following method of cleaning Diatomaceous deposits, as more 

 speedy and efficacious than any other he has tried, whether mixed with 

 soun(hngs, guano, or with mud, &c. : — " Dissolve out the lime compoimds, if 

 present, by means of nitric or hydrochloric acid, wash, and fflter. Then put 

 the moist contents of the fflter into a porcelain capsule with enough strong 

 sulphuric acid to make the whole a fluid mass. Heat the capsule over a spiiit- 

 lamp until the organic matters are aU charred, and continue the heat until 

 strong acid fiimes are evolved. Keep the capsule hot, and add, in minute 

 portions at a time, ffnely powdered chlorate of potassa. If the acid is hot 

 enough to give off fumes, the chlorate 'v\all be immediately decomposed with- 

 out the accimiulation of explosive gases, and it will exert so powerful an 

 oxidizing action, that in a few moments a carbonaceous material as black as 

 ink will become perfectly clean and colourless. Nothing now will remain to 

 be done but to wash off the acid, which is best done by the addition of water 

 and repeated decantations. I would also advise that the materials thus cleaned 

 should not be dried, but should be kept in bottles with a little alcohol, which 

 prevents their felting together, and does not allow the growth of the byssoid 

 plants which often develope in water. 



" It is necessaiy to caution those not familiar with chemistry against using 

 the chlorate of potassa with sulphui^ic acid in any other way than above di- 

 rected, as violent and dangerous explosions might result. The process as 

 above given is perfectly safe and very effective." 



Another plan of separation of the shells of Diatomeoe or of Foraminifera 



