154 



CHEMISTRY. (CHEMICAL ANALYSIS.) 



as starch, dextrines, pectines. gums, saccharifiable 

 cellulose, and organic acids, represent, with water, 

 the larger part of the elements obtained in the 

 pulpy fruits. The sugar, which is all assimilable, 

 performs its part in alimentation. The fruits 

 that contain most of it. like bananas, dates, and 

 figs, constitute real hydrocarbon aliments. The 

 extractive matters also act similarly to sugar, 

 but in- a less degree, their coefficient of digestibil- 

 ity being not quite so high. With a few excep- 

 tions, M. Balland finds the fruits not very nutri- 

 tious, and suitable to be regarded rather as con- 

 diments. 



M. F. Parmentier has shown that the effects 

 produced upon glass, hitherto supposed to have 

 been caused by fluorides, in certain mineral waters 

 are due to a'deposit of silica. No trace of flu- 

 orine has been detected in numerous analyses of 

 mineral waters. 



The adulteration of sumach was illustrated 

 by Mr. S. J. Pentecost in the reading of a paper 

 before the Nottingham section of the British So- 

 ciety of Chemical Industry. By means of strong 

 nitric acid the true sumach leaf may be dis- 

 solved out of a mixture. By aid of the micro- 

 scope the various constituents of the residue can 

 be referred to their true origin. The appearance 

 of the leaves of the adulterants generally used 

 is very characteristic, they differing from one 

 anotheV and from the genuine plant by the shapes 

 of the hairs attached to the leaves and by the 

 shape and number of the stomata. The author 

 pointed out that, notwithstanding the introduc- 

 tion of synthetic dyes, the subject is of interest 

 to the dyer as well as to the tanner. 



The examination of air and its dust has en- 

 abled M. A. Gautier to establish the fact that 

 iodine is really found in the air. It is completely 

 fixed in the organic state in the matter caught 

 by plugs of glass wool. Sea air contains about 

 thirteen times as much iodine as that found in- 

 land. Aerial iodine appears thus to come prin- 

 cipally from the sea, which is continually giving 

 up a portion of its iodized elements in the form 

 of aqueous dust. M. Gautier claims to have 

 proved the complete absence of alkaline or alka- 

 line-earthy iodides in the air, even in several 

 hundred litres collected on the surface of the 

 ocean. So that not only the presence of iodine 

 in appreciable quantities in sea water still re- 

 mains uncertain, but even the existence of this 

 iodine in the form of mineral iodides does not 

 rest on any direct proof. M. Gautier concludes 

 from his investigations that the water of the 

 open sea. or at least of that at or near the sur- 

 face, does not contain a trace of alkaline or 

 earthy iodides; that iodine is always found in 

 easily weighed quantities, but that it exists en- 

 tirely in the organic or organi/ed state a cir- 

 cumstance which has been overlooked till now, 

 and to which are due the contradictory opinions 

 that have been expressed as to the quantity and 

 even as to the appreciable presence of iodine in sea 

 water. For the origin of this iodine the author 

 looks below, whence it must come in the form 

 of iodized springs or volcanic emanations, or by 

 solution of submarine rocks. Numerous terres- 

 trial iodized springs are known, and there is no 

 reason why they should not be supposed to exist 

 in the ocran. Submarine volcanic eruptions have 

 been observed in every ocean, and their products 

 have long been known to contain iodine; and 

 iodine exists in granitic and calcareous rocks, 

 which may become dissolved in the sea water. 

 This mineral iodine dissolved in the deepest parts 

 of the sea disappears in the upper layers, where 

 the action of light permits organization and life. 



M. Gautier has found iodine existing in appre- 

 ciable quantities in terrestrial and fresh-water 

 algae, where it can only come from the water in 

 which these algae live. Analyses of the waters 

 of the rivers Seine and Marne have revealed the 

 presence of small quantities of iodine, partly 

 soluble. This, the author assumes, is derived 

 partly from the air, but principally from the 

 earths and rocks over which the water flows. 

 " The importance of the estimation of small quan- 

 tities, both in air and water," M. Gautier says, 

 " of an element so active as iodine admits of 

 no doubt; this body is indispensable to organ- 

 ized life, but the smallest proportions suffice." 



Prof. James Dewar affirms that liquid air can 

 be of great service in the qualitative analysis of 

 mixed gases. He further describes an apparatus 

 which he has used for ascertaining the propor- 

 tion of any gas in air which is not condensible 

 at about 210 C. under atmospheric pressure or 

 is not soluble in liquid air under the same con- 

 ditions. With this apparatus he has found one 

 part of hydrogen in a thousand of air just de- 

 tectable in the form of an uncondensed residue. 

 It is possible also to condense all the constitu- 

 ents of coal gas and to separate them after lique- 

 faction by fractional distillation, except carbonic 

 oxide and hydrogen; and ultimately the carbonic 

 oxide is condensed, leaving the hydrogen alone in 

 a gaseous state. Experiments with the gases of 

 the spring at Bath proved it possible to separate 

 helium from other gases when it is present to the 

 extent of only one part in a thousand. Argon, 

 which is present in the proportion of 1.4 per cent., 

 condenses with the nitrogen. But if the liquid 

 be allowed slowly to boil away a residuum may 

 be obtained containing about 7 per cent, of argon. 

 Argon when frozen solidifies to a perfectly clear 

 ice. As to behavior toward the Rontgen rays, 

 argon appeared relatively more opague than either 

 oxygen, nitrogen, or sodium, and on a level with 

 potassium, chlorine, phosphorus, aluminum, and 

 sulphur. By filling the annular spaces between 

 the walls of several similar vacuum vessels, such 

 as Prof. Dewar uses in his extremely low tem- 

 perature investigations, and exhausting them all 

 to the same low pressure, large differences in the 

 thermal isolation were observed. Silica, char- 

 coal, lampblack, and oxide of bismuth all increase 

 the insulation to four, five, and six times that 

 of the empty vacuum space; and generally the 

 presence of certain finely divided solids in the 

 high vacuum space improves the heat insulation, 

 while in the presence of air the same bodies facili- 

 tate the transference of heat. But " in no case 

 was the diminution of the influx of heat in the 

 case of the use of finely divided solids ever so 

 effective as a high vacuum in an empty tube, the 

 glass surfaces being silvered." These experiments 

 show that liquid air can be conveniently used to 

 study many important problems of heat trans- 

 mission. When cooled to the temperature of 

 liquid air the photographic action of both the 

 incandescent lamp and the Rontgen radiation was 

 reduced to 17 per cent, of that exerted at the 

 ordinary temperature, whereas the ultra-violet 

 radiation was reduced to about 6 per cent. 



Miscellaneous. An instance of the occur- 

 rence of copper in the plant world is noticed by 

 G. B. Frankfurter in the case of an oak tree in 

 Minneapolis, Minn., in which, on cutting up the 

 trunk, a considerable quantity of bright copper- 

 colored powder was noticed disseminated through 

 the pores of the wood. A quantity of the powder 

 was examined, and was found to be pure metallic 

 copper. The different parts of the tree were 

 examined preliminary to analysis, and certain of 



