November 30, IS*).] 



SCIENCE. 



719 



of ten per cent of burnt magnesia, or even baryta or 

 strontia, mixed cold with ordinary linseed-oil paint, 

 and enough mineral oil to envelop the alkaline earth, 

 will protect iron by its permanent alkaline action, the 

 free acid of the paint being neutralized. — [Build, 

 news, Sept. 14.) c. e. o. [414 



Asphalt mortar. — A composition of coal-tar, 

 clay, asphalt, resin, litharge, and sand, an artificial 

 asphalt, has been used for some years with perfect 

 success on the Berlin-Stettin railway for wall-copings, 

 water-tables, and similar places requiring a water- 

 proof coating. It is applied cold, like ordinary cem- 

 ent. The space to be covered is thoroughly dried 

 and cleaned, and then primed with hot roofing-var- 

 nish, the basis of which is also tar. The mortar is 

 then spread cold with the trowel, to a, thickness of 

 three-eighths of an inch. If the area is large, another 

 coat of varnish is given, and rough sand strewn on. 

 The material is tenacious, impregnable to rain or 

 frost: a piece exposed four years to the drainage of a 

 slope thirty-three feet high is perfectly sound, and has 

 required no repairs. — ( Centr.-blaU. bauverw. ) c. E. G. 



[415 

 AGRICULTtJRE. 



Relative value of soluble and reverted phos- 

 phoric acid. — Experiments by Voelcker gave no re- 

 sult, the dififerences between the unmaniired plots 

 being greater than those between manured and un- 

 manured plots. Wildt, in experiments in five differ- 

 ent places, found in one case that the soluble form 

 gave the greatest increase, in three cases no effect 

 could be observed from the phosphoric acid in any 

 form, and in one case the results were contradictory. 

 — (Biedecmaiui'scen()-.-6/a((., xii. 514.) H. P. A. [416 



Influence of quality of seed upon the crop. — 

 One of the most important conditions of a successful 

 vegetation experiment is uniformity in the seed used. 

 With this in mind, Hellriegel has invesrtgated the 

 effect of variations in the absolute weight, and in 

 the specific gravity of seeds upon the growth of the 

 resulting plants. He finds, that, of seeds (of barley) 

 having the same specific gravity, the heavier seeds 

 produced at first more vigorous plants than the 

 lighter. As the plants continued to grow in good 

 soil, the differences gradually diminished, until, at 

 tlie time of harvest, they had entirely disappeared. 

 When llie plants grew in poor soil, the effect of differ- 

 ences in the seed was more lasting, and even affected 

 the total weight of the crop. Differences of specific 

 gravity in seeds of the same weight produced no rec- 

 ognizable effect upon the crop. The stage of ripeness 

 of the seeds affected the development of the plants 

 in the same direction as it did tlie absolute weight 

 of the seeds; the riper seeds being heavier, and pro- 

 ducing the most vigorous plants, and the differences 

 being most manifest on a poor soil. Essentially the 

 same results were obtained in experiments with po- 

 tatoes. The attempt was also made to raise potatoes 

 of greater or of less specific gravity, by selection; the 

 heaviest or lightest being contiimally selected for 

 seed. The experiment was continued through three 

 seasons, with a negative result. — [Ibid., xii. 530.) 

 u. V. A. (417 



MINER ALOGT.? " ' 

 Albite. — This mineral usu.ally occurs somewhat 

 impure, owing to the presence of small quantities of 

 potassium and calcium. C. Baerwald claims to have 

 found for the first time a perfectly pure albite from 

 Kasb^k, Caucasia, in which no trace of potassium 

 or calcium could be detected, and which yielded, on 

 analysis, SiO., (GS.75) . Al.,0;, (19.73) . Na..O (12.29) = 

 100.77; gravity, 2.C1S. This albite is regarded as of 

 special interest in relation to T.schermalv's theoi-y, that 

 the soda-lime felspars are all isomorphous mixtures, 

 of a pure soda felspar (albite, Na.,Al5Si|iO,c) with 

 a pure lime felspar (anortbite, CaAI^Si^Os), giving 

 a continuous series between the two extremities which 

 vary in physical properties. Pure albite not being 

 known, an idea of its properties was arrived at by 

 calculation, and the author regards it of interest to 

 compare the albite from Kasb(;k with the theoreti- 

 cally pure albite of Tschermak. 



FODND ON ALBITE CALCUI.ATED BT 



FRoj( Kasbkk. Tschermak. 



Gravity 2.618 2.624 



Angle of base on bracliyplnnacoid, 86° 22', greater than 86* 29' 



When examined with crossed nicols and sodium 



light, the extinction upon a basal section was found 



to be 2° 17i'on either side of the twinning-plane; and, 



with a section parallel to the brachypinnacoid, the 



extinction took place at an inclination of 18° 23|'. 



These values vary considerably from those arrived 



at by Schuster, respectively 4° 30' and 19°; but the 



author regards his values as especially correct, being 



obtained by experiment on pure material, and not by 



calculation. — (Zeitschr. knjsL, viii. 48.) 8. L. p. 



[418 

 GBOGRAPHir. 



(Arctic.) 



Population of the Chukchi peninsula. — Dr. 

 Aurel Krause gives a resume of the exploration of 

 this district from the middle of the seventeenth cen- 

 tury, and a discussion of the ethnic relations of its 

 people, largely from the observations of himself and 

 brother during their late travels. To this is added a 

 small ethnological map, showing the distribution of 

 the various stocks on either side of Bering Strait ; and 

 a valuable vocabulary, chiefly of Chukchi words, but 

 containing also some words of the Asiatic Eskimo, 

 and some recognized as jargon. — {Deutsche rjeogr. 

 blatter, vi. 3. ) w. n. D. [419 



Hydrography of the Siberian Sea. — Otto Pet- 

 tersson contributes to the second volume of the ' Sci- 

 entific results of the Vega expedition ' a study of this 

 subject, illustrated by charts of the Kara Sea, and of 

 that part of the Arctic Ocean between Novaia Zemlia 

 and Bering Strait which has been named the Norden- 

 skiiild Sea. An important part of the paper consists 

 in the discussion of the muvements of the ice in the 

 Kara Sea, which, the author concludes, depend less 

 on wind and weather than on the varying amount of 

 warm surface-water which enters the Kara basin in 

 different years. This warm water depends largely 

 upon the discharge of the great Siberian rivers, and 

 differs according to the lime when the ice in them 



