464 



SCIENCE. 



neath the Solar action incomparably more accentuated 

 than those exhibited by the Earth. 



As no rotatory motion has ever been observed in 

 comets or their atmospheres, we feel authorized in say- 

 ing that if it does exist it is exceedingly slow, without 

 taking into account the fact that comets always present 

 the same side to the Sun. The second method of heating 

 should therefore be produced. In every plain passing 

 through the centre of the Sun and the nucleus, there will 

 be a double atmospheric circulation. On the interior, the 

 comets advance towards the Sun as though the gravita- 

 tion there was intensified. On the exterior, they deviate 

 as if the gravitation was diminished, or rather as though 

 there existed some repulsive force emanating from the 

 Sun, affecting the exterior surface of thecometary atmos- 

 phere, and acting solely upon it. In reality, this repulsive 

 force does not exist. It seems as though it did, however, 

 and under conditions analagous to those inferred by M. 

 Faye. All the consequences therefore, which he deduced 

 in order to explain the formation of the tails, are developed 

 naturally. There is nothing here to be altered. 



I do not think, however, that this theory is sufficient to 

 account for cometary appearances. On the contrary, it 

 is my opinion that electricity has a great deal to do with 

 them. But before entering upon this let us first return 

 to terrestial phenomena. 



It has been satisfactorily proved that considerable 

 electricity exists in atmospheric altitudes, and that it in- 

 creases according to the height. It is admitted gener- 

 ally that atmospheric motion results ; that it is developed 

 by evaporation at the ring of aspiration ; that it moves 

 from the time it leaves this ring until it reaches the poles 

 under the form of two currents in the rarified air which 

 it illumines. Towards the sun it is the zodiacal light, 

 invisible when close to this planet, but extending a suffi- 

 cient distance to be perceived, especially near the equa- 

 tor. Close to the poles it is the aurora borealis, which 

 we see obliquely and which appears more luminous than 

 at the zenith, because it has greater density and is more 

 concentrated. 



Upon a comet the warmth occurs at the point where 

 the trade winds come together opposite to the sun. But 

 analogous electric actions should be manifested, illumin- 

 ate the head and produce the appearance of effluviums 

 succeeding each other like the stratifications in a Geissler 

 tube, accompany the counter trade winds to the opposite 

 side to illumine the tail, and be prolonged to a great dis- 

 tance like the luminous rays in Mr. Crookes's appara- 

 tuses. No doubt, matter would be contained in the tail, 

 but rarified to an extreme degree and made visible by 

 both the solar light and the electric current. 



M. Flammarion would be quite right then to attribute 

 this shining to electricity. On the other hand, M. Ber- 

 thelot's observation would be justified, and the develop- 

 ment of this electricity would be due to the phenomena 

 of evaporation and movement situated in the atmosphere. 

 We must insist upon this point. 



The recent study of cometary spectra has shown us 

 beyond the possibility of a doubt that the interior aureole 

 and the tail contain carburetted gases which emit a light 

 of their own. Now, they can only become luminous in 

 two ways ; either by combustion or by an electric efflu- 

 vium. If by combustion, we have yet to explain how they 

 take fire and how they continue to burn indefinitely, 

 which seems very difficult. For in this case, all the 

 materials of which the comet is composed would be red, 

 and the spectrum would contain the bright spectral rays 

 of the metals as we see them in the electric arc burning 

 n mid air. Nothing of this kind occurs. The light is 

 absolutely like that of the arc when the vaporous carbon 

 is transported to the torpid gases without burning. It 

 shows no brilliant metallic bands, any more than this arc. 

 The light, therefore, cannot be the result of fire, but is due 

 to illumination made by the currents. 



I think that the Sun determines gaseous currents in 



cometary atmospheres analogous to terrestrial trade 

 winds and counter trade winds ; that this circulation pro- 

 duces near the Sun effluviums arising from the head of 

 the nucleus and transports to the opposite side the 

 substances which are on the exterior, producing upon 

 these substances the effect of a repulsive force emanating 

 from the Sun, a force which has absolutely no raison 

 d'etre. Besides this, I think this circulation is accom- 

 panied by an electric movement which illumines the gases 

 either towards the head or tail, as the case may be, making 

 them visible to us notwithstanding the feebleness of their 

 density, and precisely on account of this feebleness. 



AMYLOSE : ITS CONSTITUENTS AND METHODS 

 FOR THEIR ESTIMATION. 

 By H. W. Wiley, Lafayette, Indiana. 



I propose the name Amylose for all the varieties of 

 sugar and sugar-like substances derived from starch. 



These substances are now known by many different 

 appellations, and often the indiscriminate use of these 

 terms gives rise to a great deal of misunderstanding and 

 confusion. Among them I may mention grape sugar, 

 starch sugar, dextrose, dextrine, glucose, maltose, fruit 

 sugar, etc. These names do not always have the same 

 signification in different localities. For instance, glucose 

 and dextrose, in Europe, signify the same product, while 

 in this country they embrace many other substances 

 besides. 



If we designate the starch sugar in general by amylose 

 then the terms glucose, dextrose and maltose can be 

 used to designate certain definite constituents of amylose. 



Amylose is composed of three principal ingredients. 



1st. Dextrine. Pure dextrine is very difficult to obtain. 

 It is obtained almost pure by the dry roasting of starch. 

 The temperature during torrefaction must not be carried 

 too high, 2io°-275 c> . Starch itself has a specific rotatory 

 power of 214 ('). Bondonneau (loc. czt.), asserts that 

 there are three dextrines, (it); in which aj ( 5 ) = i86°; (/?), in 

 which aj = 176" ; (>'), in which aj = 164 . According to 

 Musculus and Grubber ( 3 ), there are five dextrines ; viz. : 



(a) , soluble starch colored wine red by iodine aj = 218; 



(b) , Erythro dextrine, red color with iodine; rotating 

 power not given. 



(c) , a Achroodextrine, not colored by iodine, j = 210. 



(d) , p Achroodextrine, aj = 190. 

 (V), y Achroodextrine, aj = 150. 



Of these varieties the first and second do not reduce 

 the alkaline copper solutions while the others do. If the 

 reducing power of dextrose be taken at 100, that of the 

 third of the above dextrines will be 12 ; the fourth 12 and 

 the fifth 28. 



O'Sullivan admits the existence 'of but one dextrine 

 with a = 214. 



Thoms'n( 4 ) tries to show by history of multiples in 

 the rotating power of the carbo-hydrates that there are 

 at least three dextrines in which the value of aj is 186, 176 

 and 164 respectively. 



I will not multiply authorities concerning the rotating 

 power of dextrine. I have quoted enough to show the 

 highly chaotic state of our knowledge on the subject. 



The chemical properties of dextrine are equally as 

 undeterminable. 



Gentele ( 6 ) is quite confident that dextrine will reduce 

 the alkaline copper solutions and on this he bases his 

 method of separating dextrine from other reducing sub- 

 stances by ferricyanide of potassium. 



Stommer ( 6 ), Bondonneau ( 7 ) and Rumpff ( 8 ), are equally 



(') Bondonneau, Bcr. d. Deu. Chem. Gesel., IX, 69. 



( a ) a = specific rotatory power. 



(8) Comptes Rendus, 1. XXXVI, 1459. 



{*) Her. d. Deutech. Chem. Gesel., 14— 2-158. 



( r, l Ping. Journal. CI, II. p. 139. 



(«) » " CLVin,p.40. 



( 7 ) Hull, dc la Soc. Chim., 1874, XXI, p. 50. 



( 8 ) Zeit. fur Anal. Chem., 1870, p. 358. 



