June ist, 18S7.] 



SCIENTIFIC NEWS. 



ful apparatus called an Osmogene, made by Messrs. Lecointe 

 and Villette, of St. Quentin, France. It has been known 

 that molasses, which is obtained as a bye-product in the 

 manufacture of sugar, contains a certain amount of sugar 

 which cannot be recovered by the ordinary way, as the 

 salts in the molasses prevent the crystallisation of the 

 sugar. The difficultj', however, can be overcome by 

 osmose, and if on one side of a parchment membrane 

 there is hot molasses and on the other side hot water 

 the required action will take place. Some of the water 

 will pass through the membrane to mix with the molasses, 

 while some of the soluble salts in the molasses will pass 

 in the opposite direction to mix with the water. The result 

 is that the water becomes more or less charged with salts, 

 and the molasses are proportionately freed from them. 

 From this it follows that a portion of the sugar which at 

 first could not be crystallised can now be recovered, the 

 salts which prevented this crystallisation being no longer in 

 the molasses, or, at all events, being present in such small 

 quantities that they do not prevent the sugar from crystal- 

 lising. 



The apparatus referred to is shown in the accompanying 

 illustration, and from this it will be seen that there are 



It was proved by the late M. Boussingault that plants trans- 

 pire an immense amount of invisible moisture from their 

 leaves, and that this moisture is supplied from the roots. 

 Now, if the root pressure is great, and the evaporation is 

 checked, the sap is forced into the plant, and escapes in a 

 visible form by the outlets supplied by nature. Dr. Mool, 

 of Amsterdam, six years ago, in special experiments on the 

 subject, placed the leaves of plants under the most favour- 

 able conditions for the excretion of drops, and substituted 

 for root pressure, a pressure produced by a column of 

 mercury. Out of sixty plants of different kinds and ages, 

 the leaves of twenty-nine excreted drops without being in- 

 jected, thirteen leaves became injected and excreted drops, 

 and eighteen became injected and did not excrete at all. 



Mr. Aitken continued the experiments. He removed a 

 branch of the poppy, which had shown a strong tendency 

 to exude moisture, and connected it by means of an india- 

 rubber tube, with a head of water of about forty inches. 

 After placing a glass receiver over it, so as to check evapo- 

 ration, it was left for three hours, when it was found with 

 drops of water at difterent parts of the edges of the leaves. 

 He noticed in the leaves of broccoli that the moisture 

 collected on them was not deposited according to the laws 



MACHINE FOR OSJIOSING MOLASSES. 



several vertical frames squeezed together by a screwed 

 shaft and wheel. The frames are made of wood, and on 

 each one there is stretched a parchment diaphragm. The 

 hot molasses is poured in through the funnels A A, and the 

 hot water through C and C. In each of the four angles of 

 each frame there is a hole, one at the bottom for the ad- 

 mission of molasses and one at the top for the outlet of 

 molasses osmosed ; also one at the opposite corner at the 

 bottom for the admission of water and at the top for 

 the outlet of water osmosed. The tube C with a funnel at 

 the end is to allow air to escape from the molasses outlet. 

 The funnel B is for testing the osmosed water. By treat- 

 ing the molasses in several frames successively a large 

 proportion of the soluble salts is removed, and the sugar 

 remaining can then be crystallised. 



TRUE AND FALSE DEW. 



AS stated in our last number, Mr. John Aitken, F.R.S.E. , 

 attacked the established theory of dew in two essential 

 points, viz., as to its formation, and as to its nature. It was 

 convincingly shown that the theory of Wells, according to 

 which the dew falls from the air above, is untenable ; and 

 that, on the contrary, it rises from the ground below. We 

 now consider his conclusions upon the nature of dew. 



of radiation or condensation ; but that it appeared in little 

 drops placed at short distances apart, along the very edge of 

 the leaf, whilst the rest of the leaf was dry. The moisture 

 was not equally distributed, but appeared in large isolated 

 drops. On further examination, by placing a strong light 

 below the blade, he observed that the position of the beauti- 

 ful sparkling diamond-like drops which studded its edge 

 had a definite relation to the structure of the leaf; they 

 were all placed at the points where the nearly colourless 

 and semi-transparent veins of the leaf came to the outer 

 edge. He fitted a full-grown leaf into the apparatus and 

 applied the water pressure. In an hour it exuded water, 

 and soon got studded with drops along its edge in exactly 

 the same way as was observed on it in the garden on a 

 summer morning. A young leaf was subjected to the same 

 test, but it did not excrete at all. 



On colouring with aniline blue the water which was 

 to be injected into the leaf, it was seen that, after the 

 pressure was applied, the drops which first appeared were 

 colourless; but in a short time the blue tint appeared. 

 This showed that there was at first very little water in the 

 veins. Soon the whole leaf got richly coloured with a 

 healthy blue-green hue, the injected fluid having penetrated 

 through it all. 



He next selected a turf of grass, and placed over it a glass 



