Scientific and Useful.

Bruce Herald, Volume IX, Issue 804, 19 May 1876, Page 3

Scientific and Useful.

APPLES AS FOOD.

The value of apples as food^eapecialljr when the apples are roasted, is hardly yet recognised among us as it ought to be, but their value in feeding cattle is comparatively unknown, except in America, where it has been discovered by accident. Here we occasionally give a horse an apple by way of a treat, and^ ifc is well known that the animal considers it a luxury; but, except we get rid of windfalls by giving them to the pigs, we make no use of apples as cattle food. In America, however, apples are more plentiful than with us, and sometimes tbey have so many that they did not know what to do with them. Hitherto there bas been an idea that they did harm if given to horses or cows, but a Mr Storer has come to their defence, and has demonstrated that, if given in combination with some highly nitrogenous food, they are not only harmless but profitable, though he will not go so far as to accept the popular rule that they are about equal in value to their own weight of potatoas. The chief thing noticed in the chemical constitution of the apple is its lack of albuminoids as compared with carbohydrates. The proportions are—albuminoids, 143 ; carbo-hydrates, including fat, 9259 j cellulose, 554 ; ash, free from carbon and carbon oxide, 146 ; and the proportion of dry matter in the fresh material, 16 84. Neither apples nor palp from cider-mills ought, thinks Mr Storer, to be wasted or merely used as manure. THE^FOOD EQUIVAI/ENT OF HEALTH. General Sherman, in bis chapter on the " Military Lessons of the American War," says: — " To be strong, healthy, and capable of the largest measure of physical effort, the soldier needs about 31bs gross of food per day, and the horse or mule about 201bs. An ordinary army waggon drawn hy six mules may be counted on to carry 30001bs net, equal to the food of a full regiment for one day ; but, by driving along_ beef cattle, a commissary may safely count the contente of one waggon as sufficient for two days' food for a regiment of 1000 men ; and as a corps should have food on hand for twenty days ready for detachment, it should have 300 such waggons as a provision train ; and for forage, ammunition, and other necessary stores, it was found necessary to have 300 more waggons, or 600 waggons in all for a corps de amnee. Each regiment ought usually to have one waggon for convenience to distribute stores, and each company two pack-mules, so that the regiment may always be certain of a meal on reaching camp without waiting for the larger trains." A curious calculation of a similar nature exists, made by Tempelhoff, a Prussian geueral, the historian of Frederick's wars :—" 100,000 men," he says, *" consume daily 150,000)bs of flour, equal to 200,0001bs of bread. Bread and forage are seldom to be had in sufficient quantities on the spot — hence magazines are established along the line of operations. The bread waggons carry a supply for six days, the men for three more. In commissariat waggons flour for nine additional days could be conveyed— one waggon to J.OO men for nine days ; thus 1000 waggons supplied the army for^hat time. An operation of eighteen days' duration could thus be conducted without an intervening magazine, but field ovens were required to make the fiour into bread. But bread for three days requires two days to bake it; at the end of six days, therefore, a halt must be made to bake, or else the ovens would fall behind with the supply* bo that, in advancing into an enemy's country before magazines could be formed there, six days was the extent of march practicable without a halt/ USE OF WASTE SUBSTANCES. In nothing has the advance of practical science been more clearly evidenced than in the extent to which substances formerly wasted and lost are now reclaimed and made to constitute an important element in the profits of the manufacturer. One of these applications consists in the recovery of soapsuds from the washing of wool in woollen factories. These were formerly allowed to run down the sewers and into the streams, to the great pollution ofthe latter ; but in Bradford they are now run from the washing bowls into vats, and there treated with sulphuric acid. The fats rise to the surface in a mass pf grease a foot or more in thickness, which is carefully collected and treated in various ways, mostly by distillation. M ~ TV products are grease, used for lubricating the cogs of drivingwheels in the mills ; eouC- acld * whl J eh 18 worth about £30 per ton, _. r *d used as a substitute for olive oil; stearin*? worth £80 per ton, &c. It is said that £ome large millowners are now paid from £500 to £1000 for these sude, which n few years ago were allowed to run waste. PREPARATION OF EBONITE. The use of ebonite, one of the newer preparations of indiarubber, is constantly increasing, on account of its better applicability to many purposes in the arts than its near ally, vulcanite. The two substances are quite similar, being composed of indiarubber and sulphur, with some preparation of gutta percha, shellac, asphalte, graphite. &c, although these latter are not essential. In vulcanite the amount of sulphur may reach as high as .60. An increased temperature is also required for this preparation. The approved formula consists in i mixing together 100 partg of rub ' ber, 45 bf sulphur, and 10 of guttapercha, with sufficient heat to facilitate the combination. In manufacture, a sufficient quantity of this mixture is placed in a mould of a desired shape, and of sach material as will not be affected by the sulphur contained in the mass. It is then exposed to heat of about 315 Fahrenheit and a pressure of about 121bs to the square ineb, for two Jiouw, Thii w done

■ m"6Bt''VreadilyV"Cy" :: 'pH'aeing''''tho '■ mould in a steam pan, where the requisite pressure and temperature cau easily be kept up. "When cold, the ebonite ia removed from the mould, and finished and polished in the usual manner. "WHITE TLOTJB. Those who have thoroughly investi-j gated the matter assure us that bread ' made from fine white flour is " starvation food." It does not contain the elements necessary to properly nourish and sustain the human body. If parents expect their children to grow up with good health, strong nerves, perfect teeth, good eyes and hair, they must not give them fine white flour bread as a constant article of diet. It is believed that the prevalence of early-decaying teeth and premature grayness and baldness of the head are largely due to the general use of white flour. The whole of the wheat, reduced to a uniform condition, without loss or injury of the food elements, makes a nutritious food, which contains all the elements necessary for growth and health . Fortunately many people are beginning to understand this important matter. PHOTOSTEBEOTYrY. A sheet of ordinary plate- glass, larger than the picture to be repioduced, is coated in the dark room with a solution made by dissolving 1 ounce of potassium bichromate in 15 ounces of water, warming gradually, then adding two ounces of fine gelatine and filtering through linen at the boiling heat. A diapoeitive is taken from an ordinary negative, and laid with the collodion side to the gelatine face of the prepared plate in diffused light for ten to thirty minutes. The plate is then taken from the frame in the dark room and washed with water for five or ten minutes, till the relief is fully developed, after wbich it is dried with filtered paper and coated with glycerine by means of a camei'shair pencil, and the excess of liquid is removed with filter-paper. From this plate a cast is made in plaster of Paris of the consistency of oi', and from the plaster : cast a metal one may be taken. ' NEW DISCOVERY IN PHOTOGRAPHY. A curious statement has appeared (remarks the 'London and Provincial Illustrated Newspaper') in some of our scientific journals, regarding a case of small-pox which was discovered by photography. A person, feeling indisposed at°the time, but not seriously unwell, attended at a studio to bave a portrait taken, and tbe photograph of the face showed it covered with distinct marks, none of which, curiously enough, were apparent upon the sitter. A day or two afterwards, however, we are told, smallpox spots broke out all over the face, where they had been foretold by the camera. The explanation of the matter is simple enough, for the photographic lens often gives us impressions of objects invisible to the eye, while we, again, see things of which photography takes no notice. Another case is mentioned of a photographer who had, as a sitter, a lady with a blui&h eruption on her face, and this he prophesied would be scarcely visible in the picture, as blue and white act pretty well in the same way upon the photographic film. He turned out right in his prognostication?, but, strange to say, spots appeared on tbe other side of the face in the picture, of which there was no trace visible to the naked eye until a few days afterwards. We may, therefore, be able to use photography one of these days as an aid to forming a diagnosis, and we shall have physicians, perhaps, applying the camera to their patients '■ as frequently as .hey do the Btethoscope.