NEWS ADD VIEWS.

New Zealand Herald, Volume XXXVI, Issue 11162, 7 September 1899, Page 3

NEWS ADD VIEWS.

SOMETHING ABOUT EXPLOSIVES. Is Cassier's Magazine (U.S.), Hudson Maxim writes:—"ln the popular mind, many erroneous impressions prevail concerning the combustion of gunpowder, and the meaning of the word explosion. There are two ways in which explosive compounds are consumed. One is called detonation, which is a form of reaction so rapidly propagated through the explosive body that it is termed an explosive wave. By the other method, the explosive body is burned from exposed surfaces, and is merely a form of rapid combustion. Detonative substances are usually termed high explosives. Those which bum from surfaces may be termed combust explosives. Combust ire explosives, requiring an appreciable time for their consumption, are adapted to use as gunpowder. by giving the projectile time to bo moved forward in the bore of the gun before ! the complete consumption of the charge, thus providing space for the products of combustion, and obviating dangerous pressures. The best form of gunpowder grain is one whose consumption will bo completed at the instant before the projectile leaves the gun, and one so formed as to present the minimum surface to the flame at ignition, aiul the maximum surface at the instant before complete consumption. Such forms of grains produce what is called progressive combustion, by which the pressure is well maintained behind the projectile throughout the entire length of the gun. Such progressive combustion is best secured by multi-perforat-ing the grains, as is done in the MaximSchupphaus smokeless powder. Explosive compounds contain sufficient oxygen for their own combustion, and do not require atmospheric oxygen. Black gunpowder is a mechanical mixture of combustible substances. usually sulphur and charcoal, with some salt rich in oxygen, such as nitrate of potassium, termed saltpetre. It- requires about 751b of saltpetre to supply the oxygen for burning 101b of sulphur and 151b of charcoal. When black powder which has been pressed into hard cakes, or prisms, is fired in a gun, the small particles of saltpetre and sulphur at the surface instantly fuse, and combine with one another and with the adjacent particles of charcoal, forming sulphate and carbonate of potash, setting free carbonic acid gas, nitrogen and carbonic oxide. The sulphate and carbonate of potash may bo termed the ash of tho gunpowder. These solids constitute about 56 per cent, of the total weight of the products of combustion ; only about 44 per cent, therefore, are gaseous. Smokeless powders are explosives in which the oxvgen is in chemical union with the combustible elements— and hydrogen. The products of combustion of smokeless powder, being practically ali gaseous, it is easy to understand why it is so much more powerful than black gunpowder."

NATIONAL PORTRAIT GALLERY. The National Portrait Gallery was founded in 1857. its birthplace being Great Georgestreet. Westminster. In 1870 it was transfelted to South Kensington, where it stavejl till 1885. Here it was at once popular, for, according to its 42nd annual report, in the year of its changing house, 58,913 persons visited it, as against only 21,757 in 1869, its last year of sojourn in Westminster. From 1885 to 1896 it lived at the Bethnal Greert .Museum, where, during which time 110 record could be kept distinguishing those who specially visited the gallery from those who visited the museum. But in 1896 it reopened in its present quarters in St. Martin's Place, and in this year 214,100 visitors passed the turnstiles. In all, omitting the uncountable visitors during the 10 years at Bethnnl Green, the gallery lias since its beginning been visited by 1,994,493 persons. During 1898 45 new portraits were added to the gallery, raising the total to 681 in all. There are many subjects of deep interest among the new additions. Sir John Moore, K. 8., by Sir Thomas Lawrence; the Arctic Council discussing a plan of search for Sir John Franklin ; the immortal David Garrick, by Luke Sullivan ; Charles Dickens by Daniel Maclise ; and last, but not least, William Ewart Gladstone by G. F. Watts. There is a rule that 10 years must elapse from the death of a celebrity before bis portrait may appear in the gallery. But the rule has been provided with an exception in the case of Mr. Gladstone.

ACTIVITY IN IRON TRADE. The solid character of the revival in the iron trade is emphasised by the marked improvement shown in the exports of iron and steel in the last two months. The total for June is 324,944 tons, against 275,034 tons in June. 1898, an increase of 49.910 tons, and in May the quantity was 374,374 tons, against 298,641 tons in May, 1898, an increase of 75,733 tons. The movement in prices, say Messrs. Fallow and Co. in their trade circular, was very pronounced during these two months, and " the situation appears to grow stronger as time goes on. High though prices may appear, it is not improbable they may go higher still." The price of pig-iron has risen now to 71s 8d for Scotch or Cleveland, and ,77s 4d fur hematite ; on the 7th inst. the figures were 70s 4d. 69s Bd. and 75s 4d. while on April 7 they were 54s 6d, 48s 3d, and 58s 9(1, respectively. and on December 31, 1898, 49s 6d, 44s 6d, and 565. As a natural consequence, prices of iron and steel have advanced since January 1 about 30s to 40s per ton.

CONCERNING THE KILT. There is an illuminating Scotch proverb to the effect that " ye canna tak' the brecks off a Hielandman and it is generally held to imply that it is easier to get blood out of a stone than change oat of a Scotchman who lias gone to London to make his fortune. Its more obvious meaning is that the Highlander is invulnerable where his breeks are concerned, because lie hasn't any. " Instead of which," as the judge remarked to the prisoner, "he goes up and down the country wearing a kilt." It is a matter less of economy than of custom : and he curries the custom about the world with him. It is true that out of the myriad Scotchmen—artists and others—who are making handsome incomes in London, there are few that we see regularly in the kilt. But (writes an occasional contributor), every Highlander in London—like the soldier of the French army, who carries a baton at the bottom of his knapsackconceals a kilt at the bottom of his Gladstone, and a sympathetic thrill from every Scotch bosom will go out to the Clan Macdonald, in Patersons, New Jersey, who are martyrs in the cause of this sacred garment. The Clan Macdonald is a respectable organisation of MacGregors, Frasers, Stuarts, and Buchanans, who are manfully striving to uphold the banking accounts of their race on the alien soil of the United States. Four of them, in the true spirit of Scotch humour, volunteered to bring out the garment of their clan from the recesses of their carpet-bag. and entertain the Young Men's Christian Association of the neighbourhood with s. Highland fling in costume. But the local secretary, a man with no breadth of mind, misunderstood the offer, and caustically remarked that in his opinion a Highland fling was rather worse than a corps de ballet. He suggested as a compromise that the Highlandmen should wear long skirts, plaid trousers, or bloomers.

In exposed situations wind-breaks for fruit plantations exposed to violent gales or cold winds are highly desirable and necessary. Writing on this subject the Agricultural Gazette lately stated that some growers plant bolts of damson trees, but theso harbour llio vermin which attack plums as woll as damsons. Other? plant whitethorn, which makes a dense fence, but is very slow in growing, The hornbeam is quicker to grow, and makes a good fence, but harbours the caterpillars of the winter and other moths. In the Scilly Isles, the enonymus, escallonia, and veronica are used as wind-breaks, and they stand the sea air well, but would not flourish in a bleak climate. The enonymus mnJtes a capital fence, and is not liable to any insects which attack fruit trees; but it is somewhat slow in growth. The black poplar is quick, but is not easily made into a dense fence. On the Duke of Bedford's fruit farm thero is a wonderful fence of the American crab which has grown up very quickly; but it is liable to caterpillars which attack apples generally. Mr. R. L. Castle, the manager, recommends the Plum Cherry or Myrobalam (Prunus cerasifera) as a quick grower, and as liable to no important insect attack but that of aphis, which is easily dealt with. An extensive fruitgrower m Bedfordshire has divided his plantations into sections with hedges of this tree, and they are now 15ft or muro in height. TO CYCLISTS. I/it of Henning and Dunlop tyres for sale, from 15s, slightly Henning, Stanlevstreet.