DISCOVERY OF TRIPOLI OR POLISHING POWDER. 



up in one nf your muslin filtera. A common 

 pocket Icnife in the most oonvenient tool for 

 thin purpoM but • painter'n fipat\iU makea 

 much neater work, and I have often wished 

 that I had one that would shut up in its handle 

 Bo as to lie carried in the pocket. When you 

 have got your K<^therinK n|M)n your filter you 

 fold it up as you woulu a powder in a paper, 



idace it in the bottuiii of your box and k<> <»* to 

 ook for another, liy placing each gathb.'ing 

 immediately above the preceeding one you 

 keep them in their proper order and can tel! 

 when you take theui out attain exactly where 

 each of them cauie from, thus enabling your- 

 self to dispense with attaching i,ny memoran- 

 dum tag or Ial>el. On getting h )me you take 

 each filter by itself, wash otf tlie deposit in a 

 separate wide mouthed phial, i'jt it settle and 

 examine it at your leisure. 



MICK08C0PES. 



Very high-priced micmscopes are not a 

 necessity for the study. For 94U or $50 you 

 can now buy one that will show you all that 

 anybody but a specialist wants to know alxiut 

 the Diatoms and many another curious little 

 form bettides. The Industrial Publication 

 Company of New York 'nanufact'iro iind sell 

 an excellent little instrument of this class for 

 935. 



FUHHIL DIATOMS. 



Diatoms are found in the fossil as well as in 

 the recent condition, and any streaks of light- 

 cobired earth exposed in u cutting ot about the 

 banks or b«<l of a drained lake or pond are al- 

 ways w^rth in vestigatiug. If, in addition to 

 its peculiar light grey or blueit^h grey color, the 

 earth is also very light in weight, the probab- 

 ility of its being i>iat<>(nace(>UM is much in- 

 creased. These foHsil Diatom beds represent 

 what were once the basins of lakes, ponds or 

 seas that have been long dried up. Similar 

 l>eds are now in process of formation at the 

 bottoms of our own lakes and seas, destined 

 perhaps to be uncovereii and studied some 

 centuiirs hence by Home future generation of 

 iibservers. The little flinty shield or skeletons 

 (if these plants are very <lur»ble and ^e^isl 

 most of the usual agents of diitiutegration which 

 cHUses the structures of higher organisms to 

 dixappear so rapidly after death. Perfect forms 

 are found in guano which have resisted at least 

 two or three digestions and )x>Hsib!y uiore. 

 The birdnget them from the fish, who pMbably 

 had them from the mollU'<ks,and after all these 

 digesi tons we still find them well enough pre- 

 served to mount fir tho microscr»|>e. Some of 

 these fossil Diatom berls are very extensive. 

 Hooker speaks of a submarine one not less 

 than 400 miles l<mg and 120 broad, situated 

 upon the banks of Victoria Island, in lat. 78 

 deg. S , and at a depth of 200 to 400 feet. A 

 stratum 18 feet thick underlies the city of 

 Kichmonl. Va , and exten Is over an area 

 whose limits are not known. The strata at 

 Bilin in Bohenda, from which the Polier 

 Scbiefer or polishing slate is taken in Urge 

 quantities, to be ufed as an article of com- 

 merce, averatse 14 feet thick. The '"Turkey- 

 atone," used fur sharpening edge tools upon, 

 is composed of an agktregation of Diatoms that 

 have Deen consolidated and altered by heat, 



and the large quantities of flinty (siliceous) 

 matter foimd in the chalk }mU are believed to 

 have had a siudlar origin. As a single cubic 

 inch of Diat4>maceou8 earth contains some mil- 

 lions of individual forms, we can get some 

 fitint idea of the enormous imwers of multipli- 

 catiim (MtHsessed by these hun'Sle little plants. 

 Their remains extend over such areas and 

 reach to such depths as to constitute no incun* 

 siderable part of the crust of the globe. 



Mr. e. F. Natthewa* AddroM. 



Dr. Allison has described to you the Dia- 

 toms as they ap|>ear to the naturalist, and I 

 pro|>oBe to say a few words about them from 

 an economical p<dnt of view and as witnesses 

 to the past history of this region. The deposits 

 in our lakes and ponds are largely made up of 

 one or the other of two kinds of organisms; one 

 consisdng of shells of molluscous animals, chief- 

 ly water snails; the other of such diatomaceoui 

 structures as the doctor has descril>ed. To the 

 former class belong the marl beds of Lawlors' 

 or Torryhurn Lake, which have been exposed 

 to view and rendered accessible for examina- 

 tion by the draining of that lake -an operati. 3 

 effected many years ago in connexion with the 

 building of the Intercolonial Railway. To the 

 latter class apiiertains a deposit recently dia« 



covered at 



FITZUERALI) L'VKB, 



a pond seven or eight miles from St. John in 

 the direction of Lake Lomond. We may hope 

 that the owner of this lake, Mr. Wm. Mur- 

 dock,may make it available for scientific study 

 by draining off the water that now conceals 

 the xilicious earth at the bottom. The study 

 of these lake deposits is of some importance, as 

 they are likely to throw li»(ht on the former 

 physical conditir)n of this region and to give in- 

 formation concerning the vicixsituiles through 

 which it has passed since its land surface em- 

 erged from l>eneath the waters of the Post- 

 pleiocine Sea. Hy taking the history of the 

 numerous lake basins which are scattered over 

 the surface of the land in this neighborhood (as 

 shown by a s<urly of the deposits they contain), 

 beginning with those of the greatest elevation, 

 and following downward to those at lower 

 levels, a number of independent records may 

 be obtained, which though synchronous in their 

 latter parts are separated in time in their be- 

 ginning, and thus will supply a successive 

 chronological history of the later changes which 

 the land surface of the country has undergone. 

 The deeper beds of these lake-deposits are of 

 course the older, and are, therefore, of by far 

 the greater interest in their bearing on the 

 physical history of our land. In thia connex- 



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