November, 1905.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



267 



cause the dust nuclei in the air to become centres of 

 condensation, and that is the case even with the very 

 smallest dust-particles. 



If part of the cotton-wool be taken out of the filter 

 and only enough be left to keep back all but a few- 

 particles, and these of the very smallest size, yet 

 these require but the very slightest expansion to make 

 them visible. If the process of successive expansions 

 be continued, no further condensation is observable. 



Now, introduce a little musk into the flask. If the 

 musk gives off solid particles, cloudy condensation 

 would at once take place when the air is expanded by 

 drawing- the handle of the air-pump, because the musk 

 would keep up a constant supply of nuclei of con- 

 densation. But it is found that instead of that, the 

 condensation is scarcely visible at first, and finally 

 ceases, as if no musk were present at all. In conse- 

 quence, it is determined that musk does not give off 

 solid particles. 



Varying this experiment. Dr. Aitken considered that, 

 if musk passes into the air as a gas or vapour, it would 

 be able to pass through a quantity of cotton-wool 

 sufficient to stop all dust-particles. He first passed 

 air over the musk, then through the cotton filter, with 

 (he result that the perfume came freely through the 

 cotton-wool. Some of the gas which first entered the 

 filter was trapped and held by the wool, but the wool 

 soon became sufficiently saturated to allow the musk- 

 vapour to pass. The trapped vapour remained in the 

 wool and could easily be detected afterwards. 



He also tested other odorous solid substances by 

 the same simple apparatus, such as camphor and 

 naphthalene. These both acted like musk and gave no 

 nuclei of condensation, and the gas or vapour from 

 both passed easily through cotton-wool. It is, there- 

 fore, safely concluded that they, like musk, evaporate 

 in gaseous form. Quite conclusively, Dr. Aitken has 

 similarly tested twenty-three substances ; not one of 

 them gave off their perfume in solid particles, nothing 

 but gases or vapours escaping from them. 



By repeated experiments. Dr. Aitken has come to a 

 remarkable conclusion, which will be interesting to 

 sanitarians, viz., that sewage does not communicate to 

 the air any solid particles. The offensive emanation 

 is a gas. The air in sewers is remarkably free from 

 germs of all kinds, as they do not leave the sewage. 

 If sewage gave off solid or liquid particles, these also 

 would soon settle on (he surface of the sewage. If, 

 however, it be made to flow rapidly over falls, 

 then both germs and particles of the sewage get mixed 

 up with the air, but when the sewage flows without 

 break in its surface film, the offensive emanation is in 

 the form of a gas. 



This revolutionary theory will take some trouble to 

 crush. And it will in future save the sensitive feelings 

 of those who have been unduly puzzled with the ex- 

 treme division theory of matter in the case of con- 

 ^•eying scent from the perfumed body. 



Sta-r Ma-ps. 



We regret that, at the last, it is not possible to bring 

 out a star map supplement for this number. Not 

 satisfied with the results of the process hitherto em- 

 ployed, we have been testing new methods, which, it 

 is hoped, ^vill give much better results. The (rials, 

 however, have not been completed in time for this 

 month, although we hope with the December issue to 

 continue the series. 



SugOLr. 



By Dr. F. MoLtwo Perkin. 



Although the sweetness of most fruits is attributable 

 to their sugar content, there are comparatively lew 

 which contain saccharose, the sugar which, in this coun- 

 try, is generally called cane sugar. Of all plants which 

 contain saccharose, the largest quantity is found 'n 

 the sugar cane, as may be seen from the following 

 list : — 



15 to 20 per cent. 



Sugar Cane Saccharbiiim offiihuiiiim 



Sugar Beet Betii vulgaris 



Sorgo, Soi'gliiim sacchaiatiim 



Pine Apple 



Sugar Maple, Acer Scuclniiiiiinii 



Strawberry 



Apricots . . 



It is also found in small quantities in some varieties 

 of birch, palms, and in maize stalks. Most other 

 plants contain either grape sugar (dextrose), or fruit 

 sugar (laevulose). 



Cane sugar seems to- have been first Known to- the 

 Chinese, at any rate, they knew of the sweetening pro- 

 perties of the sugar cane, although it is doubtful 

 whether they actually prepared crystallised sugar. At 

 the time of Alexander the Great, sugar was brought 

 into Greece, and the Grecian doctors employed it in 

 medicine for curing all kinds of disease. The crystal- 

 lised sugar appears to have been first prepared during 

 the 7th century A.D., and was manufactured in Persia 

 in the 8th century. The preparation of sugar and the 

 cultivation of the cane followed in the steps of " the 

 conquering Moors," during the 9th and loth century, 

 when it was introduced into Sicily and Spain. Fig. i., 

 taken from an old engraving, shows the manufacture 

 of cane sugar in Sicih' in the year 1570. 



In the i5(h and T6th century it was introduced by the 

 Portuguese and Spaniards intO' Madeira, Brazil, and the 

 Spanish West Indies. From this time on the cultiva- 

 tion of the sugar cane in the tropical countries, and 

 (he production of sugar, became a greater and greater 

 industry. Many refineries of the raw sugar, obtained 

 from abroad, were set up in Europe, and continued to 

 flourish for many years, until, in 1806, Napoleon pre- 

 \ cnted (he importation of the raw product. This practi- 

 callv killed (he cane sugar industry on the Continent, 

 but it resulted in the initiation of the beet sugar manu- 

 factory, which to-day is playing such havoc with the 

 cane sugar industry. In this article the cane sugar 

 industrv will be first dealt with, as it is of greater 

 antiquity, and also because the methods employed are 

 simpler than tluisc in operation in the beet sugar 

 manufactory. 



The chief cane sugar producing districts are Cuba, 

 Java, Manilla, Mauritius, the West Indies, Northern 

 India, North America, Brazil, Japan, China, Egypt, 

 and the Sandwich Isles. In India it is being intro- 

 duced with the hope that the cultivation of sugar, and 

 its manufacture, may, to some extent, take the place of 

 the waning- indigo industry. 



The sugar cane, as has already been shown, may, 

 under favourable circumstances, contain from 18 to 20 

 per cent, of sugar, but when the agricultural and cli- 

 matic conditions are not favourable, the amount of 

 sugar may not be more than 15 per cent., as, for 

 example, in Louisiana. The sugar cane belongs to the 



