SCIENTIFIC.

Otago Witness, Issue 1854, 3 June 1887, Page 36

SCIENTIFIC.

; _____ Scientific ra^n inform. us that we can distingish only some six varieties of substances by taster These are f the- bitter, sour,, sweet, saline,- alkaline, : atid "metallic. r ' Othierseriumerate simply • the' 'sweets and < bitters; 1 acids • arid ' salines as -, the *'f our varieties 'of savours we are able to distinguish. v'THe' rapidity -'with which 'different -substances" may be perceived and appreciated by- the sense of taste varies greatly. 1 For example, salt ranks 1 highest HDn the list': : It can!b*ei tasted in'-O\L7 of a' second after its application. - Qninine.-with'a much more" persistent" flavour, requires- but -0-258 of a-second'forjits,-appreciation by taste. "Bitters' do not. rank highly in 1 the matter of -food appreciation. Sours and sweets come i certainly within the range of taste. We have acquired a'habit of referring every sensation 1 about- the 'friouth to taste, whsreas, in- reality, it is argued Iby the London News, smell has .more'tp J do : with the],matter than is really'believed. '' Even' in the'case'of sweets and- sours, it can hardly, oe" denied that these "are to-be distinguished more by a combination of smell, taste, and touch than by taste alone:"- Again, we discriminate degrees of sourness by -smell in a ready fashion," and such degrees- may.be tested and distinguished by the more delicatesmell when taste lags woefully behind in the work of discrimination. Perchance it" is the • pure sweet savour that>taste has the right to assume as -its - special province. ' Yet " lengthened sweetness long drawn out " will weary the palate unless it ' is linked^ to some other ■ flavour iti the distinction , of which, smell may play a part. Children will weary of plain sugar, 'while the' flavoured candy attracts them 'more powerfully; and this is a proof of the argument- that it is to' smell and to its aid in tasting that the higher sense of gratification is due: ■■ -

The chemistry of iron and steel is yearly becoming of greater and greater importance ; in fact, in all the branches of metallurgy it is being recognised that thescientific chemist's aid must be ■ called in; and that old rule-of-thumb methods devised centuries ago must give- way to others ' in- harmony with bur nineteenth - century ■ knowledge. - Since chemists' have turned -their ,'attentidns i to alloys 'every year sees' the production' of new ones with valuable properties. The latest discovery in this field relates to the effect ofsilicon in iron,which has'been shdwn to exercise a remarkable ' influence on' the amount' of carbon which can combine : with iron, and can thus by its presence determine whether- a- sample of iron-will come out with the properties of cast' iron, steel, or wrought iron. The discovery is sure 1 to prove, of great importance to the steel industry. When iron is' got to 1 alloy with a large proportion of' silicon, it- becomes quite rustproof.

Sir William Thomson, in a recent lecture at the Royal Institution, enunciates a new theory concerning the original condition of the sun. He suggests that its mass , was formed by .the collision of two c6ol bodies coming together with the' velocity due to their ' mutual gravitation. This theory is supported by 'the physical law that two bodies at rest in space, if free from the dis-, turbing., attraction of other bodies, wouldcertainly collide with direct impact, . and hence with no rotational' momentum of the compound body formed by the collision.. , The velocity which a body thus, falling into the sun wouldacquire is more than 30 times that which' our earth; has in "its orbital motion. The earth speeds along its orbit at a rate ' exceeding 18 miles per second, but a body falling freely into the sun would have a velocity of 380 miles per second. Sir William Thomson, therefore, . calculates .that if two cool, solid globes, each of the same mean density as the earth, and of half ' the 1 sun's diameter, and twice the sun's. distance from the earth, should collide, the collision would last for a few hours, in the course of which they would be' transformed " into a violently agitated incandescent fluid mass, with about 18,000,000 years' heat ready made in it, and swelled out by this heat to possibly one and ahalf times, or two, or three, or four times the sun's present diameter." • ' ' . ,

In a paper just published in Nature, Mr Eric'S. Bruce, the English inventor of the balloon for signaling by the electric light, announces, that he will soon put his invention to the most rigorous of tests — signaling across the English channel at Dover, Mr Bruce's balloon 1 is, made of a perfectly, translucent material, filled with hydrogen or coal gas, in the interior of which are placed several incandescent electric lamps, The lamps are in metallic circuit with a source of electricity on the ground. In the circuit; on the ground is an apparatus for making and breaking contact rapidly, and by varying the duration of the flas'-K- if li^ht in the balloon it is possible to signal by the Morse or any other code. '

A curious heating apparatus has been discovered and devised by Professor Morse, of Salem, Mass. It is a most interesting and practical method of utilising the sun's heat for " artificial warming-." The deyice consists simply of a shallow box, the bottom' of which is corrugated iron, and the top of glass. This is placed outside the building in such a position that the sun shines , directly j upon it, the heat rays of the sun pass i through the glass and are absorbed by the iron, heating it to quite a high temperature, and, by a system of, ventilation, a current of air is passed through the apparatus and into the room to be heated. By. this .means- the air was heated on pleasant .days to. about 90deg by passing over the iron. Rays bf the sun are also utilised for motive fppwer by the illustrious Swedish-American, engineer, ' John Ericsson, who is now.m. his 84jbh* > year-^' j and he is said to, be working in his .shop <10 hours daily, jthe^l'sun motor ?' having;.been "his chief object of. study and experiments for the last 20 year's. •* ' ■

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