264 



CHEMICAL COMPOSITION OF FOSSIL LINGULJS. 



[1854. 



possible to explain, in some instances, some of the visible pheno- 

 mena on mechanical principles? May there not be, in the case of 

 many volcanoes, rude natural channels and reservoirs within the 

 stratified parts of the earth's oust, into or through which the 

 fiery fluid may pass, on its rising towards the surface — channels 

 which, having a certain amount of inclination, may cause liquid 

 lava to act as water in the hydraulic ram, producing earthquake- 

 shocks when the throes are ineffectual — and ejections of matter 

 high into the air, when a passage has at last been cleared ? — 

 reservoirs, in the shape of huge natural caverns, which, gradu- 

 ally becoming tilled with the rising fluid, produce, by atmos- 

 pheric compression over its surface, a continuous stream for a 

 time — like the air-box in the fire-engine ? 



I conclude with the remark that in Canada — in western Canada, 

 at least — we appear to be happily situated outside the circle of 

 dangerous volcanic influence, it is true we now and then hear 

 of vague rumblings at St. Catherines and Dundas; of a sort of 

 volcanic tide-wave in the Lake near Cobourg; of detonations on 

 the north shore of Lake Huron. We are assured, also, that an 

 undulation of the earthquake at Lisbon in 1755 was felt on Lake 

 Ontario. We know that in 1663, in the lower portions of the 

 Province, there was an earthquake with volcanic ashes, which 

 lasted for six months; that in 1785, and again in 1814, at Que- 

 bec, there was pitchy darkness at noon-day, with black rain and 

 volcanic ashes — due, it has been supposed, to a crater in the 

 terra incognita af Labrador. We can see, moreover, that the 

 basin of Lake Superior, in the far dim foretime of this continent, 

 was a focus of volcanic action. We notice trap in the river Ste. 

 Marie, and Gros Cap is porphyritic. Col. Fremont describes an 

 extinct crater in the neighbourhood of the Great Salt Lake, and 

 an active volcano, 70 miles to the north-east of San Francisco. 

 Mount Elias, in the Russian territory, is an open volcanic vent. 

 And Commander MeClure, of the Investigator, reports lava 

 along the American coast of the Polar Sea. But in Canada, on 

 the whole, it is a matter of congratulation that we have thus far 

 been permitted to acquire a strong confidence in the ground on 

 which we tread, and that we are spared the presence amongst 

 us of any of those points of communication between the upper 

 and nether worlds — which in other lands are exceedingly inte- 

 resting, — but also sometimes very inconvenient. 



On tlie Chemical Composition of Recent and Fossil Lingnlflo 

 and some oilier Sliells** 



By W. E. Logan, F.R.S., and T. S. Hunt. 



In the Report of Progress of the Geological Survey of Canada 

 for 1851-52, we have mentioned the existence of small masses, 

 containing phosphate of lime, and having the characters of cop- 

 rolites, which occur in several parts of the Lower Silurian rocks. 

 In a bed of silicious conglomerate towards the top of the calcife- 

 rous sandstone, at the Lac des Allumettes, on the Ottawa, they 

 are abundant in cylindrical and imitative shapes, sometimes an 

 inch in diameter. The same material forms casts of the interior 

 of a species of Holopea or Pleurotomaria, and often fills or com- 

 pletely incases the separated valves of a large species of Lingula, 

 which Salter has referred to L. parallela of Phillips. The phos- 

 phatic matter is porous, friable, and of a chocolate brown color ; 

 it contains intermixed a large quantity of sand ; and small peb- 

 bles of quartz are sometimes partly imbedded in it. The analysis 

 of one specimen gave 36 per cent of phosphate of lime, with 55 



* See page 195 for a previous notice of this discovery. 



per cent, of carbonate and fluorid, besides some magnesia and 

 oxyd of iron, and 50 per cent, of silicious sand. 



Similar masses occur in the same formation at Grenville, and 

 in the lower part of the Chazy limestone at Hawkesbury, in both 

 cases containing fragments of Lingula. Those from the latter 

 place are rounded in shape, and from one-fourth to one-half of 

 an inch in diameter, blackish without, but yellowish-brown 

 within, and having an earthy fracture; the analysis of one of 

 them gave: 



Phosphate of lime, (P0 5 , 3Ca 0), - 44-70 

 Carbonate of lime, - 6-60 



Carbonate of magnesia, .-- 4-7G 

 Peroxyd of iron, and a trace of alumina, 860 

 Insoluble silicious residue, - 27-90 



Volatile matter, .... 500 



97-56 



From the color it is probable that the iron exists as a carbon- 

 ate. When heated in a tube, a strong odor like burning horn is 

 perceived, accompanied by ammonia, which reddens tumeric 

 paper, and gives white fumes with acetic acid, showing that a 

 part at least of the volatile matter is of an animal nature. The 

 specimens from Lac des Allumettes lose 1-7 per cent, by gentle 

 ignition, with a like production of ammonia, and an odor of ani- 

 mal matter; the same thing was observed with those from Gren- 

 ville. 



The existence in Lower Silurian rocks of these masses, whose 

 characters leave no doubt that they are coprolites, and whose 

 chemical composition is like that of the excrements of creatures 

 feeding upon vertebrate animals, led us to examine the shells of 

 the Linguke always associated with these phosphatic bodies. The 

 result has been that all the specimens yet examined consist chiefly 

 of phosphate of lime; they dissolve readily with slight efferves- 

 cence in hydrochloric acid, and the solution gives with ammonia 

 a copious precipitate readily soluble in acetic aeid, from which 

 oxalic acid throws down lime. With a solution of molybdate of 

 ammonia there is obtained a quantify of the characteristic yellow . 

 molydo-phosphate, many times greater than the bulk of the 

 shell. 



We have thus examined Lingula'prima and L. antlqua, from 

 the Potsdam sandstone, L. parallela from the calciferous, and a 

 species somewhat resembling L. quadrata from the Trenton 

 limestone. It was desirable to compare with these the shell of 

 a recent species, and for this purpose fine specimens of the Lin- 

 gula ovalis of Reeve, from the Sandwich Islands, were furnished 

 us by J. H. Redfield, Esq. of New York. The shell of this spe- 

 cies had the same composition as the fossil ones, and the thick 

 green epidermis, which swelled up like horn when heated, gave 

 a bulky white ash of phosphate of lime. 



For a further analysis the shell was boiled in water to remove 

 all soluble matters, the soft parts still adherent were carefully de- 

 tached, and the shell, with its epidermis weighing -186 grammes, 

 was calcined over a spirit lamp. The brownish residue, weigh- 

 ing -114 grammes, readily dissolved with slight effervescence, in 

 dilute hydrochloric acid, leaving but a few light flakes of carbon- 

 aceous matter. Acetate of soda and perchloride of iron were 

 added to the solution, which was boiled, and the precipitated basic 

 salt separated by filtration, and decomposed by hydrosulphuret 

 of ammonia. The filtrate from the sulphuret of iron having been 

 concentrated, the phosphoric acid was thrown down by ammonia 

 with a magnesian salt; there was obtained '070 grms. of pyro- 



