342 



♦ KNOW^LEDGE ♦ 



[Dec. 7, 1883. 



neighbourhood of the equator, be carried upward by the 

 heated air which gives rise to the trade winds. But in the 

 northern hemisiihere the trade winds blow in a north- 

 easterly direction, and this theory will not account for 

 the carriage of dust to India, which lies to the north- 

 west of Java ; or to South Africa, whicli lies in a 

 south-westerly direction. The fine dust of the Sahara, 

 carried upward by exceptionally strong sirocco winds, 

 occasionally reaches Rome and Florence, but all traces of 

 it are lost as far north as Paris and London. It seems, 

 therefore, very improbable that terrestrial dust should be 

 carried upward by the wind and distributed over a whole 

 hemisphere. It may be suggested that dust was on 

 this occasion projected by the volcanic forces to a 

 far greater altitude than the altitude reached by 

 the dust from the Sahara. But dust projected with 

 great velocity would be rapidly stopped by the resist- 

 ance of the atmosphere, and would not, unless borne away 

 by the wind, be carried as far as stones and large 

 masses of scoriis. It will hardly be suggested that 

 the volcanic cloud over Krakatoa was carried upwards 

 by the heat of the eruption, and spread outwards 

 over a whole hemisphere, drifting against the prevailing 

 winds to India and South Africa. But the volcanic 

 theory is completely negatived by the observation of the 

 blue sun setting in the fiery heavens as seen from Trinidad 

 (near to the centre of the opposite hemisphere from the 

 Krakatoa eruption) on the 2nd of September, for it cannot 

 be supposed that the volcanic matter was carried half round 

 the earth in the period of seven days which elapsed between 

 Sunday, the 26th of August, when the .lava eruption began, 

 and Sunday the 2nd of September, when the blue sun was 

 seen setting at Trinidad. 



There remains the not improbable supposition that the 

 earth has encountered a cloud of dust in space. In a paper 

 published in the Ilonthhj Notices for January, 1879, 1 have 

 collected a series of observations which show that meteoric 

 dust is continually being deposited on the earth's sur- 

 face. 



To account for the simultaneous phenomena observed in 

 India and the West Indian islands, it is necessary to sup- 

 pose that just before Sept. 2 the earth passed through a 

 region of space more than ordinarily rich in the dust which 

 we know is so widely distributed in space. 



If the dust-laden region was so large that the earth 

 occupied many hours in passing through it, we may expect 

 to find that the phenomena caused by the presence of dust 

 in the higher atmosphere have been observed over more 

 than a hemisphere of the earth's surface. We may also 

 learn something as to the time which small particles 

 of dust occupy in sinking to the earth from the 

 higher regions of the atmosphere, where they are first 

 brought to rest. Possibly months, or even years, 

 may be occupied by the finer particles in the process of 

 sinking to the ground, for small particles of dust are 

 probably carried upwards by convection currents in the 

 daytime and sink again during the night. Prof. C. A. 

 Young has shown that threads from a gossamer spider, 

 attached to a stick, fioat upwards when exposed to the 

 sun, while they sink when the stick is removed into the 

 shade. Such small bodies, when exposed to the sun, seem 

 to be involved in a film of heated air, which is suflicient to 

 raise them, and will even raise the Ijody of the gossamer 

 spider as well as his web in the summer air. 



It is well known that a fall of snow brings down quan- 

 tities of meteoric particles, and it will be a matter of inte- 

 rest to observe whether the first fall of snow greatly 

 affects the red sunset phenomena. Judging from the dura- 

 tion of the after-glow, it seems probable that much of the 



dust may still be above the region of cloud formation.* 

 No doubt the larger particles fell in the first few weeks, 

 for the blue appearance of the sun when near the horizon, 

 as seen through the clear air of the tropics, has passed away. 

 I imagine that the whole of the phenomena observed may 

 be accounted for by the mere presence in the upper at- 

 mosphere of a larger amount of dust than is ordinarily 

 suspended there. It is known that water in which fine 

 dust is suspended assumes a beautiful blue colour, and 

 small particles suspended in the air probably produce a 

 similar effect. We are perfectly familiar with the blue 

 colour of the dispersed light from the heavens, and if 

 the amount of dispersed light were greatly increased, it 

 is only to be expected that the colour of the dispersed 

 light would sensibly affect the colour of the more intense 

 transmitted light. 



The green colour afterwards seen when the sun was close 

 to the horizon is, of course, easily accounted for by a com- 

 bination of the ordinary absorption of the blue end of the 

 spectrum with the absorption of the red end producing the 

 blue colour, so that only the green or middle part of the 

 spectrum was left. The red and orange tints of the after 

 glow would be caused in the same manner as the ordinary 

 sunset tints, only being exaggerated by the longer course 

 of the rays through the atmosphere. 



THE CHEMISTRY OF COOKERY. 



By W. Mattied Williams. 



XXIV. 



SINCE the publication of my last paper, I have learned the 

 proper name of the Swiss compound there described as 

 fondevin, according to my recollection of its pronunciation 

 in Switzerland. In an old edition of Mrs. Rundell's 

 "Domestic Cookery," it is described as "/oiidu." A 

 similar dish is described in that useful book " Cre-Fydd's 

 Family Fare," under the name of " Cheese Sovjfte or 

 Fondu." I had looked for it in more pretentious works, 

 especially in the most pretentious and the most disappoint- 

 ing one I have yet been tempted to purchase, viz., the 27th 

 edition of Francatelli's " Modern Cook," a work which I 

 cannot recommend to anybody who has less than £20,000 

 a year and a corresponding luxury of liver. 



Amidst all the culinary monstrosities of these " high- 

 class " manuals, I fail to find anything concerning the 

 cookery of cheese that is worth the attention of my readers. 

 Francatelli has, under the name of " Eggs a la Swisse," a 

 sort of fondu, but decidedly inferior to the coxa-mon fondu 

 of the humble Swiss osteria, as he lays the eggs upon slices 

 of cheese, and prescribes especially that the yolks shall 

 not be broken ; omits the milk, but substitutes (for high- 

 class extravagance' sake, I suppose) " a gill of double 

 cream," to be poured over the top. Thus the cheese is not 

 intermingled with the egg, lest it should .spoil the appear- 

 ance of the unbroken yolks, its casein is made leathery 

 instead of being dissolved, and the substitution of six- 

 penny worth of double cream for a halfpenny worth of 

 milk supplies the high-class victim with tivepence half- 

 penny worth of biliary derangement. 



In Gouffe's " Royal Cookery Book " (the Hortsehold 

 Edition of which contains a great deal that is really useful 

 to an English housewife) I find a better recipe under the 

 name of " Clieese souffles." He says : " Put 2-^ oz. of flour 

 in a stewpan, with 1 ^ pint of milk ; season with salt and 



* The sediment from water derived from the first fall of snow 

 which occurs this year should be examined, to see whether it is par- 

 ticularly rich in particles of meteoric iron. 



