304 



NA TURE 



[January 30, 1902 



metal-mining districts have been made ; attention has been 

 given to the possible extension of artesian water-bearing strata, 

 and also to borings in search of coal near Albany, where in all 

 cases the floor of older crystalline rocks was reached without 

 evidence of coal-bearing strata. 



From the Iowa Geological Survey, which is under the 

 direction of Dr. .Samuel Calvin, State Geologist, we have re- 

 ceived the eleventh volume, comprising the annual report and 

 accompanying papers for 1900. The papers are brief memoirs 

 on seven counties, in which the geology is described, typical 

 sections are noted in detail, fossils are recorded, particulars are 

 given of economic deposits and soils, and the papers are 

 admirably illustrated. The Survey is carried on with evident 

 vigour and ability. Special reports on coal, artesian wells, lead 

 and zinc ores have already appeared. D r. S. W. Beyer, one of 

 the special assistants, has now in preparation a monograph on 

 Iowa clays, and others are working at the materials suitable for 

 the manufacture of Portland cement. We are informed by Dr. 

 Calvin that the demand for the publications of the Survey has, 

 so far as the earlier volumes are concerned, e.\ceeded the supply. 

 Yet much ignorance prevails, and samples of yellow mica or 

 iron pyrites are received almost weekly from persons who 

 imagine they have discovered gold in Iowa ; and an important 

 part of the survey work is to prevent useless explorations for 

 geological products. 



The American Naturalist commences the year well, some of 

 the articles in the January number being of more than usual 

 interest. Among them is one by Dr. R. W. Shufeldt, on the 

 habits of kangaroo-rats in captivity, illustrated by a couple of 

 excellent photographs of these curious little American rodents, 

 taken by the author from life. The specimens, three in number, 

 which Dr. Shufeldt had under observation belonged to the 

 species known as Perodipits richardsoni, and became quite tame 

 after a few days in confinement. "They hopped about," he 

 writes, " with great agility on their hind pair of kangaroo-like 

 legs, while the little short pair of anterior limbs were curled 

 inwards on the chest. . . . They are able climbers, and the 

 rapidity with which they can dig a burrow in ordinary ground is 

 astonishing. They use the fore-feet to perform the digging part 

 and the long and strong hind-legs to kick the loosened soil out 

 of their way behind, as it accumulates every moment or so. In 

 soft soil one of these little mammals can put itself out of sight 

 in less than a minute by digging." It is added that kangaroo- 

 rats are in the habit of turning their cheek-pouches inside out 

 in order to clean them. In another article in the same journal, 

 on the best method of mounting fishes for museum-exhibition, 

 Mr. S. E. Meek pronounces in favour of quadrangular glass- 

 vessels, in which the specimens, after being painted on the side 

 to be shown with water-colours, are placed in alcohol as if 

 swimming. It is added, however, that this method, although 

 the best yet devised, is by no means perfect, and discussion is 

 invited from experts in the hope that a more satisfactory way 

 of exhibiting these animals may be devised. 



A ropiiLAR account of the principles and performances of 

 telegra])hy without intervening wires is given by Mr. S. R. 

 Bottone in his little book on "Wireless Telegraphy and Hertzian 

 Waves," the second edition of which has been published by 

 Messrs. Whittaker and Co. The first edition was noticed in 

 Nature of September 27, 1900 (vol. Ixii. p. 522). 



In the letter on the influence of temperature on the action 

 of nitric acid on metals, which appeared in Naiure of 

 December 12, 1901, the words "the temperature abruptly 

 rising from 80° C. to as much as 104° C." were printed as 

 received from Dr. A. J. Ewart, who, however, now informs us 

 that they .should read " the temperature abruptly rising to from 

 80° C. to as much as 104" C." 



NO. 1683, VOL. 65] 



A SECOND edition, revised and extended, of Dr. S. Rideal's 

 work on " Water and its Purification" has been published by 

 Messrs. Crosby Lockwood and Son. The original edition was 

 reviewed in these pages on j\pril 29, 1897 (vol. Iv. p. 602), and 

 the book remains substantially the same, though changes have 

 been made in the chapter on the characters of natural waters, 

 and there are several additions dealing with recent water 

 epidemics and with sand filtration. It is a little surprising to 

 find in a scientific book that the employment of a dowser or 

 " water-finder " is suggested, and the cautious remark is made 

 with reference to water-finding that " if further research should 

 discover a physical law underlying the process, its utility would 

 become more certain and extended." The same remark could 

 just as reasonably be made of astrology, chiromancy, or any 

 other process of divination. 



A CATALOGUE of protected rheostats, measuring instru- 

 ments and electrical apparatus relating to them has been 

 issued by Messrs. Isenthal and Co. The rheostats have been 

 devised to economise space on switchboards and elsewhere and 

 to minimise the chances of short circuit. In the Electra Rheo- 

 stats (Schindler-Jenny's patents) the resistance wires are em- 

 bedded in a highly refractory, insulating material, and a 

 protecting sheet of metal is cast around the latter. Instruments 

 constructed upon this plan do not possess the defects commonly 

 found in other embedded rheostats, and ihey are particularly 

 suitable as motor-starting rheostats for continuous and rotary 

 current. The Dimmer switches, also included in Messrs. 

 Isenthal's list, provide a means of moderating the light of elec- 

 tric incandescent lamps. By means of a reducing rheostat in 

 the switch the light of an electric lamp connected with it may 

 be given four degrees of brightness, from the dimness of a night 

 light to full luminosity. The measuring instruments include 

 several types of voltmeters, amperemeters, and cell testers, for 

 workshop and laboratory use. 



The twenty-third communication from the laboratory of 

 van 't HofT to the Prussian Academy of .Sciences, on the con- 

 ditions of formation of the oceanic salt deposits, contains a 

 summary of the results obtained from the investigation of 

 solutions s.aturated at 25" C. with sodium chloride and containing 

 the chlorides and sulphates of magnesium and potassium. As 

 the result of this series of researches, the conditions of existence 

 of a large number of the Stassfurt salts in contact with aqueous 

 solutions, and inversely the conditions necessary for the separa- 

 tion of these salts from the mother liquors, have been accurately 

 established. The salts or minerals for which these valuable 

 data have been obtained are— bischofite, sylvine, thenardite, 

 carnallite, glaserite, astrakanite, reichardtite, kieserite, schonite, 

 leonite and kainite, all of which may separate from solutions at 

 25° C. The two salts langbeinite and Iciweite are apparently 

 not capable of existence in contact with solutions at this 

 temperature, and their occurrence in the Stassfurt layers points 

 to the prevalence of a higher temperature than 25" C. in the 

 formation of these natural deposits. 



The additions to the Zoological Society's Gardens during the 

 past week include a Rhesus Monkey (Macaais rhesus) from 

 India, presented by Mr. C. Hunterbrocken ; a Patas Monkey 

 (Cercopilheius patas) from West Africa, presented by Mr. A. 

 Richmond ; two Sharpe's Wood Owl (Syrniitm nuchale), a 

 White-throated Monitor {Varanus albigiitaris) from West 

 Africa, presented by Mr. William Cross ; a Bengalese cat (Felis 

 fe/;^a/f/«!i) from the East Indies, two Egyptian Geese (C/i<«a- 

 lapex aegyp/iacus) from Africa, an Anaconda (Euuecles tnnrinus) 

 from South America, a Black Sternothere {Sternothaerus niger) 

 from West Africa, deposited ; a Barasingha Deer (Cerviis 

 duvaucelli) from the Himalayas, received in exchange. 



