5.^ 



♦ KNOW^LEDGE ♦ 



[Jdlt 27, 1883. 



collision of bodies travelling already through interstellar 

 space with enormous velocity ; for when we rightly appre- 

 hend the vastness of such space we see that collisions of those 

 bodies could no more occur with the necessary frequency 

 than the bullets fired by two widely-scattered bodies of 

 skirmishers could be continually encountering in mid-space. 

 We seem forced to the conclusion that the work of solar 

 condensation has gone on much farther than it seems to 

 have done — in other words, that the sun's real globe is very 

 much smaller than that globe, bounded by the photosphere, 

 which is actually seen by us. 



According to this view, the real surface of the sun 

 would lie tens, possibly hundreds, of thousands of miles 

 below the photosphere — far below even the lowest of those 

 lo%ver levels disclosed in the larger sun-spots. 



That this view is correct is shown in other ways. If we 

 consider how the sun-spots shift in relative position, through 

 what is called their proper motion, we cannot but infer 

 that the cloud-laden region in which they are formed lies 

 very far from the real surface of the sun. The spots are 

 limited, as every reader no doulit knows, to two zones of 

 the solar photosphere corresponding to the sub-tropical and 

 temperate zones on the surface of the earth. Those which 

 lie nearest to the equator indicate a rate of rotation, in the 

 equatorial zone of the visible surface, carrying it round 

 once in about twenty-four days. Those which lie farthest 

 from the equator indicate a rotation period for these 

 parts of the spot zones, carrying them round once in 

 aljout twenty -four days. Now, if we assign to the 

 equatorial zone an area equal to a tenth of the sun's, 

 we have a surface exceeding the earth's 1,200 times. 

 To each of the zones of slowest motion (leaving the 

 Polar regions out of consideration altogether) we may 

 assign half this area, or to the two combined the same 

 area. The depth of the cloud-laden region in which 

 the spots are found averages certainly not less than 8,000 

 miles — or say a diameter of this earth. The volume, then, 

 of the equatorial zone of cloud-laden matter, which rotates 

 once ia twenty-four days, is certainly not less than 2,300 

 times the volume of the earth.* This also is the sum of 

 the volumes of the two spot zones farthest from the 

 equator, which rotate once in twenty-eight days. If 

 these regions were of the same mean density as the 

 sun, or about one-fourth the earth's, then the mass 

 of the equatorial region would be about 600 times 

 the mass of the earth, or nearly twice the mass of the 

 giant planet Jupiter — and each of the zones remotest 

 from the equator would nearly equal Jupiter in mass. 

 Now, it is utterly impossible that such masses if forming 

 part of a continuous atmospheric cloud-laden region, and 

 not very far indeed from the surface of any solid, liquid, 

 or highly-compressed vaporous nucleus the sun may have, 

 should be free to travel round at rates so different, 

 that the equatorial region is carried round seven times 

 while the two farther spot zones are carried round only six 

 times, the former gaining one rotation — a circuit of two 

 million miles — on the latter in 168 days, or nearly 500 

 miles per hour. Frictional resistance would undoubtedly 

 coerce the various zones of the sun's surface to the same 

 rotation rate. The cloud-laden region in which the spots 

 appear must, therefore, be very much rarer than the sun's 

 real globe, and the sun's real surface riust lie far below the 

 visible si rface. 



• It may be divided into 1,200 cubes (approximately pnongh) 

 each a terrestrial diameter in the edge, each therefore exceeding 

 the earth in volume in the same degree that a cube exceeds the 

 inclosed sphere, or as 6 exceeds tt. Putting v at 22/7, this gives 

 the ratio, 21 to 11, in which 1,200 must be increased, giving 2,300 

 approximately. 



There is another proof of the same important fact. It 

 has been shown by Professor George Dar'win that if the 

 central parts of the sun were not very much denser than 

 the rest, the sun's globe would be measurably compressed 

 at the Poles. Now there is nothing more certain than 

 that no such compression can be recognised. The meri- 

 dional observations of the sun at all the great national 

 observatories are now to be counted liy hundreds of 

 thousands, and they are all (practically) measurements of 

 the sun's disc. If there were measureable compression, it 

 would be recognised among this vast collection of measure- 

 ments. But they agree in showing no trace of measurable 

 compression. It follows that the sun's central portion is 

 much more condensed than parts near his visible surface, 

 a result agreeing with what we have already inferred from 

 two lines of reasoning, each nearly amounting to a demon- 

 stration. 



We conclude, then, that the real surface, where in all 

 probability the disturbances arise to which sun-spots are 

 due, lies tens of thousands, possibly hundreds of thousands, 

 below the visible surface, where the effects of those dis- 

 turbances are recognised. 



(To be continued.) 



CHEMISTRY OF THE CEREALS. 



By William Jagg, F.C.S. 



No. II. 



SEVERAL of the constituents of the various grains 

 with whose chemistry we are now dealing are so 

 much alike that it is difficult to determine whether it is 

 better to tirst finish what we have to say about one of these 

 bodies and then go on to the others, or to commence by 

 giving an outline of the properties of the whole, and sub- 

 sequently deal with them in detail. Thus starch, cellulose, 

 and the gum of the various cereals are identical in chemical 

 composition, and in many respects are most closely allied 

 to one another. It will probably render our work simpler 

 if we at any rate study these three bodies together. 

 Our last article will have made the reader acquainted 

 with the general properties and appearance of starch ; 

 we would now direct his attention to the next 

 member of our present group — viz., cellulose. The per- 

 centage of this body present in grains varies from 1 in 

 oats to 14 9 in maize. A passing reference was made to it 

 in our last paper, where it was stated that the outer enve- 

 lope of the starch granules consisted of starch cellulose. 

 The function of this body in plants is somewhat analogous 

 to those of the skeleton and connective tissue in animals. 

 Not only are the envelopes of the various cells of the plant 

 composed of it, but also woody fibre and the more 

 solid framework of plants consist of this compound. 

 In physical properties cellulose differs widely : the pith of 

 elder, linen, cotton wool, and some of the specially pre- 

 pared paper used by the chemist for filtering purposes are 

 nearly pure forms of cellulose. On the other hand, it 

 occurs in an approximately pure state in the " tagua-nut," 

 a substance so hard as to be capable of being turned in a 

 lath' and having every appearance of ivoiy. 



Gel. .dose, like starch, is represented by the chemical 

 formula CsHuOs, and is very jirobably derived in the 

 plant from starch. One of the greatest wonders of organic 

 chemistry is this fact of there being many substances of 

 widely different appearance and properties, and yet of the 

 same formula. Cellulose and starch are two cases in point, 

 and to these we may add a third in dextrin, or " British 



