July 24, 1890] 



NATURE 



[I 



(2) If the English units be used, the minim and the drachm 

 should not be employed at all. All weights should be expressed 

 either in grains or decimal parts of a grain, or in ounces and 

 fractions of an ounce ; all measures in fluid grains, or in fluid 

 ounces and fractions of a fluid ounce. 



B. Formula:. — (3) Formulae should give the number of parts 

 of the constituents, by weight or measure, to be contained in 

 some definite number of parts, by measure, of the solution. 

 The mixture can then be made up with (a) grammes and cubic 

 centimetres, or {b) grains and fluid grains, or (<■) ounces and 

 fluid ounces, according to the unit selected. 



(4) The standard temperature for making up solutions should 

 be 15° C. or 62° F. No appreciable error will be introduced 

 by the fact that these two temperatures are not quite identical. 



(5) Formulae should give the quantities of the constituents to 

 be contained in x parts of the finished solution, and not the 

 quantities to be dissolved in x parts of the solvent. When a 

 solid dissolves in a liquid, or when two liquids are mixed, the 

 volume of the solution or mixture is, as a rule, not equal to the 

 sum of the volumes of its constituents. The expansion or con- 

 traction varies with the nature of the solids and liquids and the 

 proportions in which they are brought together. In making up 

 a solution, therefore, the constituents should first be dissolved 

 in a quantity of the solvent smaller than the required volume of 

 the finished mixture, and after solution is complete, the liquid, 

 cooled if necessary to the ordinary temperature, is made up to 

 the specified volume by addition of a further quantity of the 

 solvent. 



(6) It is very important to specify, in the case of liquids, 

 whether parts by weight or parts by mea3ure are intended. The 

 equivalence between weight and measure only holds good in the 

 case of water and liquids of the same specific gravity : a fluid 

 ounce of ammonia solution or of ether weighs less than an 

 ounce ; a fluid ounce of strong sulphuric acid weighs nearly two 

 ounces. 



(7) Whenever possible, formulae should give the quantities of 

 the constituents required to make up 10, 100, or 1000 parts of 

 the solution. 



(8) When a mixture {e.g. a developer) is to be prepared just 

 before use from two or more separate solutions, it is desirable 

 that the proportions in which the separate solutions have to be 

 mixed should be as simple as possible — e.g. i to i, i to 2, I to 3, 

 I to 10. 



(9) When metric units are employed, the original French 

 spelling, "gramme," should be used in preference to the con- 

 tracted spelling, "gram," in order to avoid misreading and 

 misprinting as "grain." 



SCIENTIFIC SERIALS. 



In the Journal of Botany {or ]ur\t and July we find contri- 

 butions to systematic and descriptive botany by Mr. E. G. 

 Baker, on new plants from the Andes, and on the genera and 

 species of Malvea; ; by Mr. F. N. Williams, a synopsis of the 

 genus Tunka of Caryophyllacese, and others. — Mr. A. Fryer 

 records what he believes to be an example of hybridity in 

 Potamogeton. — Mr. H. T. Soppitt describes a new parasitic 

 fungus, Puccinia digraphidis, the teleutospore-form of which 

 occurs on Phalai'is arundinacea, while the secidio-form is 

 parasitic on Convallaria majalis. 



The original papers in the Nuovo Giornale Botanico Italiano 

 for July all refer to the geographical distribution of Italian 

 plants, chiefly Hepatica? and Fungi. Among the papers read 

 at the meetings of the Italian Botanical Society the following 

 are of special interest :— Signor O. Kruch contributes to our 

 knowledge of the foliar fibrovascular bundles of Isoetes. — The 

 exhaustive researches of Prof. Arcangeli on the structure of the 

 various organs in the Nymphaeaceae are represented by an account 

 of the leaves of Nymphaa and Nuphar. — Signor U. Martelli 

 gives a very interesting account of the dissociation of a lichen 

 [Lecanora subfusca) into its constituent algal and fungal elements, 

 the complement of Stahl and Bonnier's observations on the 

 synthesis of lichens. — Prof. Arcangeli describes the carnivorous 

 habits of an Aroid, Helicodiceros muscivorus. 



American Journal of Science, July, 1890. — The inconsis- 

 tencies of utilitarianism as the exclusive theory of organic 

 evolution, by Rev. John T. Gulick. The author criticizes 



NO. 1082, VOL. 42] 



various conclusions arrived at by Mr. Wallace in his volume oi> 

 " Darwinism." — The southern extension of the Appomattox for- 

 mation, by W. J. McGee. In a paper entitled "Three 

 Formations of the Middle Atlantic Slope," published in this 

 Journal YCi 1888, a distinctive late Tertiary formation well dis- 

 played on the Appomattox River in Eastern Virginia was defined 

 and named after that river ; and its principal characters, distri- 

 bution, stratigraphical . relations, and probable age were re- 

 corded. The present number contains the result of an ex- 

 tension of the research into the Carolinas, Georgia, Alabama, 

 and Mississippi. — An experimental proof of Ohm's law, pre- 

 ceded by a short account of the discovery and subsequent 

 verification of the law, by Alfred M. Mayer. The experiment 

 described is very suitable for lecture demonstration, and all 

 details are given. A low-resistance Thomson galvanometer is 

 joined up to a box containing coils of l, 2, and 3 ohms resistance, 

 and to a coil of wire wound round a disk of wood which slides on 

 an upright magnet I'S cm. in diameter. The quick movement 

 of this coil causes the production of a magneto-electric current, 

 and adopting the conception of the lines of magnetic force it may 

 be said that a ring with one coil cuts a certain number of these 

 lines, this cutting of the lines causes the current, and is the 

 electromotive force. A ring with two, three, or four coils cuts 

 two, three, or four times the number of lines, and increases the 

 electromotive force in the same proportion. The resistance in 

 the circuit can also be changed by means of the resistance coils,, 

 and hence it can be proved that the current is directly as the 

 electromotive force and inversely as the resistance by observa- 

 tions of the galvanometer deflections. — Microscopic magnifica- 

 tion, by W. Le Conte Stevens. If F be the equivalent focal 

 length of the eye-piece of a microscope, / that of the objective,. 

 T the tube length, and D the distance of distinct vision, the mag- 



_ (D + F)(T -/) 



nification, M, is expressed by the formula M 



— Notes on the minerals occurring near Port Henry, N.Y., by 

 J. F. Kemp. — Occurrence of goniolina in the Comanche series 

 of the Texas Cretaceous, by Robert T. Hill.— A method for the 

 reduction of arsenic acid in analysis, by F. A. Gooch and P. E. 

 Browning.— On the development of the shell in the genus 

 Tornoceras, Hyatt, by Dr. Charles E. Beecher. — Fayalite in 

 the obsidian of Lipari, by Jos. P. Iddings and S. L. Penfield. 

 — On some selenium and tellurium minerals from Honduras, by 

 Edward S. Dana and Horace L. Wells. The locality from 

 which the minerals were obtained is the El Plomo mine,. 

 Ojojoma District, Department of Tegucigalpa, Honduras. An 

 analysis of one showed that it contained 29 "31 per cent, of 

 selenium and 70*69 per cent, of tellurium, the great proportion 

 of selenium constituting it the nearest opproach to native 

 selenium which has yet been found in nature. It is proposed ta 

 call this mineral selen-tellurium. Some tellurium-iron minerals 

 are also described. — Some connellite from Cornwall, England, 

 by S. L. Penfield. 



American Journal of Mathematics, vol. xii., 4 (Baltimore, 

 July 1890).— This number opens with a short note (pp. 323-336> 

 on confocal bicircular quartics, by Prof. Franklin, and closes with 

 a memoir on the theory of matrices, by H. Taber (pp. 337-396. ) 

 The memoir is a full investigation of the subject, touching upon 

 the results already obtained by Cayley ("Theory of Matrices," 

 Phil. Mag., 1858), Hamilton ("Quaternions," 1852), the two 

 Peirces, and Cliff"ord. The writer was not aware of Buchheim's 

 paper, with an identical title, in the London Mathematical 

 Society's Proceedings (vol. xvi. ) until after his own paper was 

 written. There is much which is substantially the same in the 

 two memoirs, but Mr. Taber claims to have "treated the 

 whole subject more in detail and more systematically than 

 Mr. Bucheim " {sic). 



SOCIETIES AND ACADEMIES. 

 Paris. 

 Academy of Sciences, July 15. — M. Hermite in the chair. 

 New studies on the rotation of the sun, by M. H. Faye. Ai> 

 account is given of Dr. Wilsing's observations of faculae for the 

 purpose of determining the time of rotation, and of the recent work 

 done by M. Duner, in which Fizeau's method was adopted. — 

 On the photography of the polarization fringes of crystals, by 

 MM. Mascart and Bouasse. A method of obtaining photo- 



