io8 



SCIENCE. 



[Vol. XX. No. 498 



Since then they have been found in many parts of the country, no 

 less than 106 localities being now known whence they have been 

 obtained. All of these localities are naturally not equally good, 

 and many of them are not now worked at all. 



Some useful hints are given by Mr. Griswold in Chapter iv. on 

 the purchase and care of whetstones, and especially that little 

 understood matter, the use of lubricants; and in Chapter v. the 

 subject of manufacture of stones is discussed. This dates back to 

 the beginning of the Christian era at least, for definitely-shaped 

 hones are found at Pompeii. At present, in America, the stones 

 mostly come from Indiana, Arkansas, New Hampshire, and Ver- 

 mont; although there are other States producing them. The to- 

 tal out-put is small, and $75,000 would represent the value of the 

 manufactured product in 1880. 



Of the Arkansas stone proper, considered a typical novaculite, 

 only about 60,000 pounds are quarried annually. The most of 

 this goes to New York to be manufactured, whence it is largely 

 shipped back to Arkansas. The blocks are laid in plaster of Paris 

 in the bed of the gang-saw, and the saws are so arranged as to 

 waste as little as possible. The sawing is slo%v, "saws going at 

 the rate of 80 swings per minute will only penetrate the stone in 

 the gang-bed at the rate of IJ inches in 10 hours. Marble is 

 sometimes sawed at a rate of nearly 8 inches per hour, though for 

 dense marble 2 inches per hour is a closer estimate." After the 

 first cutting the slabs are sorted, and the useless pieces thrown 

 away, this being done again and again as the pieces are reduced 

 in size until only 25 per cent of the original amount remains as a* 

 mai-ketable product. Of the Ouachita stone, a coarser variety of 

 whetstone, a much larger amount is produced, this being in 1889 

 1,040,000 pounds. The method of cutting is about the same as 

 for the Arkansas stone, while the waste is about 50 per cent. 



Mr. Griswold deals extensively with the petrography of the 

 novaculites, giving descriptions of numerous microscopic sections 

 from various localities. The conclusions may be summed up as 

 follows: Novaculite rocks were deposited in deep water as sedi- 

 ments, the carbonate of lime crystallizing as rhombohedrons. 

 Consolidation of the siliceous portions produced a hard, brittle 

 rock, which, being subsequently folded and elevated above the 

 sea-level, was subjected to erosion. During this process the cal- 

 cite crystals were removed, and subsequently a secondary deposit 

 of silica took place. 



In regard to the sedimentary origin of the rocks, Mr. Griswold 

 says : — 



"It may be somewhat difficult to conceive of a constant supply 

 of very fine fragmental silica, almost totally without other mate- 

 rials, in sufficient quantity to form beds several feet in thickness 

 with very thin layers of slate between, and making a formation 

 from 500 to 600 feet in thickness, yet this seems to have been the 

 manner in which these rooks were formed. After all, the con- 

 ception is not so difficult when one considers that the fragmental 

 silica of many of the slates and shales is as fine as that of novacu- 

 lite, and as the percentage of silica in the sediments forming 

 these rocks is increased, the resulting rock approaches more and 

 more closely the novaculite. Thus with the novaculites are asso- 

 ciated vtry argillaceous shales, grading into siliceous shales and 

 then into transparent novaculites. The almost absolute purity of 

 the novaculites still causes doubt as to the possibility of this mode 

 of origin; but many coarse sandstones are nearly as pure, and if 

 the novaculites can be considered as extensions of the sandstones 

 toward the deep sea, where the finer fragments would settle, then 

 we have at least a close approximation to the sediments forming 

 the novaculites. That the same action which produces the angu- 

 lar fragments of quartz in sandstones must also afford a very large 

 amount of exceedingly fine quartz is evident" (p. 192). 



Many pages of the report are devoted to detaOs of the geology 

 of the novaculite area, but it is obviously impossible to enter ioto 

 any of these here. A brief epitome only can be given of the geo- 

 logical history of the area, which in Mr. Griswold's words is as 

 follows: — 



" The sequence of events in this history seems to have been as 

 follows: A deposition of very fine fragmental material on the 

 deep-sea floor to form the Silurian strata, included in the upper 

 part of which are two groups where graplolites abound. ^At the 



end of the Lower Silurian deposition, through the periods known 

 as Upper Silurian and Devonian, there was an almost total cessa- 

 tion of the deposition of sediments. There seem to be two possi- 

 ble explanations for this fact : First, there may have been a de- 

 pression of the sea-bottom which left this area so far from shore 

 that no thick sediments were accumulated over it, and this was 

 followed by an elevation in Lower Carboniferous times renewing 

 sedimentation in perfectly conformable beds; the second explana- 

 tion is that while upper Silurian and Devonian beds were being 

 deposited elsewhere, the same period was occupied by a deposition 

 in the Arkansas area characterized by Lower Silurian organisms. 

 This continued until a decided change of conditions in Lower 

 Carboniferous times renders necessary a change in the nomen- 

 clature of the beds in consequence of the change in the character 

 of the fossils. 



"True Coal-Measure strata covered the novaculite area also, 

 for they are found in Texas in a latitude considerably south of 

 34° 30', while the trend of the formation is nearly east and west 

 through this part of Arkansas and through the Indian Territory. 

 The south members of the coal strata of northern Arkansas have 

 been worn completely away, and are now buried beneath the Cre- 

 taceous and Tertiary deposits which cover southern Arkansas. 



" Following the formation of the Coal Measures, and probably 

 synchronous with the Appalachian uplift, came the elevation of 

 Arkansas above sea-level. The time following this post-Carbon- 

 iferous elevation of Arkansas has been one of erosion, though we 

 have evidence of some periods of accumulation as well as denu- 

 dation. The three periods of accumulation were the Cretaceous, 

 Tertiary, and Pleistocene, during which there were partial and 

 perhaps complete submergences of the area" (pp. 206-307). 



The final chapter of the volume deals with the fossils of the 

 area. These, it is true, are few in number, but seem to be suffi- 

 cient to justify the assertion of the Lower Silurian age of the de- 

 posit. Dr. R. R. Gurley contributes some remarks upon the 

 graptolites found in shales both underlying and overlying the 

 novaculites. His conclusion is that two horizons are represented, 

 one of Calciferous, the other of Trenton age. Comparisons are 

 drawn between the Arkansas beds and those of Point Levis in 

 Canada, Calciferous in age, and those of Norman's Kill in New 

 York, of Trenton age. A number of new species or varieties are 

 described by Dr. Gurley. Joseph F. James. 



Wasblngton, Aug. 11. 



Outlines of Theoretical Chemistry. By Lothae Meter. New 

 York, Longmans, Green, & Co. 



The author of this volume is well known by the successive edi- 

 tions of his "Modern Theories of Chemistry" and by the share 

 that he took in developing the periodic law of the elements. The 

 larger work was translated some years ago by Professors Bedson 

 and Williams ; and the same translators have put this volume into 

 good, readable English. 



The author says (in view of the various works already published 

 on theoretical chemistry): "I have not considered the require- 

 ments of students alone, but have been desirous of ofl^ering some- 

 thing to those friends of scientific investigation who have neither 

 the intention nor the time to concern themselves with the details 

 of chemical investigation, but wish to become acquainted with 

 the general conclusions arrived at. With this object in view, I 

 have abstained from too large a use of the numerical results of 

 observations and measurements, and have avoided giving detailed 

 descriptions of experimental methods. . . . The general — I naay 

 say the philosophical — review of the subject has been my chief 

 aim, to which the details should be subordinated." 



The author's purpose, as thus expressed, has been in good mea- 

 sure carried out. Chemists wlU prefer his " Modern Theories of 

 Chemistry," if they would become really proficient in this aspect 

 of the science; and to such this work may seem superfluous. But 

 many, who are chiefly interested for practical reasons in chemical 

 analysis or manufactures, may be glad to find so good an " Out- 

 line," compressed into 216 clearly-printed pages. The work is 

 not made up of distinct chapters, but the sections seem to succeed 

 each other in natural order, giving some prominence to the fol- 

 lowing topics : Atomic theory, the several methods of determining 



