276 



KNOWLEDGE. 



[December 1, 1898. 



There is a generally accepted idea that metals have 

 smells, since if you take up a piece of metal at random, or a 

 coin out of your pocket, a smell can usually be detected. 

 But Prof. W. E. Ayrton finds that as metals are more and 

 more carefully cleaned, they become more and more alike 

 in emitting wo smell, and, indeed, when they are very 

 clean, it seems impossible for the best of noses to distin- 

 guish any one of these metals from the rest, or even to 

 detect its presence. The smell associated with metals, and 

 hitherto regarded as being due to the metals themselves, 

 is really due to the presence of some impurity, usually a 

 compound of carbon and hydrogen. Much misappre- 

 hension has also prevailed with respect to the dififusion of 

 smells. The passage of a smell is generally far more due 

 to the actual motion of the air containing it than to the 

 diffusion of the odoriferous substance through the air. If 

 the breath is held, without in any way closing the nose 

 either externally or by contracting the nasal muscles, no 

 smelling sensation is experienced, even when the nose is 

 held close to pepper, or a strong solution of spirits of 

 hartshorn. Prof. Ayrton has also carried out experiments 

 on the power of different substances to absorb various 

 scents from the air, and finds that many of the old beliefs 

 have to be exactly reversed. Thus, grains of natural musk 

 lose their fragrance at a comparatively rapid rate when 

 exposed to the air. The popular statement that a grain 

 of musk will scent a room for years is, therefore, not 

 supported by laboratory experience. The way in which 

 some smells cling to various substances is very remarkable. 

 No amount of rubbing would remove the smell of rose 

 leaves from glass. 



A French scientist has been making observations recently 

 upon double-yolked eggs, a number of which were incubated 

 for a certain time and then examined. In twenty per 

 cent, neither of the yolks developed, but were found to be 

 joined to one another by a considerable surface, and the 

 germ discs or cicatriculfe were close together. In the rest, 

 the yolks were free or but slightly joined, while the cicatri- 

 culffi were in most cases remote from one another. In a 

 third of the eggs, one yolk only developed, and it was some- 

 times that at the "big end," sometimes that at the " little 

 end" which failed; but the most remarkable feature was that 

 one of the yolks had produced a double monstrosity. The 

 remainder of the specimens showed more or less develop- 

 ment in both yolks, and in a case where both embryos 

 were normal, though the former were joined, the cicatri- 

 culiB were in their proper position at the north pole, as it 

 were, of the yolk. Other examples showed one normal 

 chick and one incompletely grown ; while in one case, and 

 this in an egg laid by the same fowl, as in the previous 

 case of a similar character, there was one normal chick 

 and a double monstrosity. The usual idea is that the 

 chickens we occasionally see preserved in spirits with four 

 wings, and as many legs, and perhaps two heads, are 

 formed from two yolks in a single egg, which have produced 

 a double monstrosity owing to pressure. But pressure 

 would hardly account for such merging of two component 

 chicks as often takes place. The researches referred to 

 show that in two cases it was a single yolk or cell which, 

 irrespective of the second, produced the double embryo. 

 These particular eggs, then, show in one and the same 

 example two kinds of twins, two young ones produced 

 together, and one egg-cell producing two young ones. 



used, the balloon being fitted with a " steering sail." A 

 Times reporter says that " We satisfied ourselves that to 

 steer a balloon to some extent by this method is perfectly 

 feasible ... for not only can one so direct the balloon as 

 to avoid obstacles, but the even altitude maintained by the 

 use of the trail rope lessens the waste of gas ; for it must 

 be remembered that though the friction of the trail rope 

 drags the balloon down, the balloon is also relieved of bal- 

 last to the extent of the rope that is on the ground — two 

 opposing forces that tend to keep the balloon in equilibrium 

 at a certain elevation." 



According to the Minim/ and Scientific Press 

 ing are the relative values of the rarer metals 

 [jiven being per one pound avoirdupois of each 



G-allium 



Vauailium 



Rubidium ' 



Thorium 



Glucinum 



Calcium .. 



Lanthanum 



Lithium 



InJium .. 



Tantalum 



Yttrium .. 



Didvmium 



Strontium 



Ariiim 



S(iS,600 

 10,7SO 

 9,800 

 8,330 

 5,800 

 4,900 

 4,900 

 4,900 

 4,410 

 4,410 

 4,410 

 4,410 

 4,200 

 3,675 



Erbium ... 



Ruthenium 



Niobium 



Rhodium 



Barium ... 



Titanium 



Zirconium 



Osmium 



Uranium 



PallailiuiM 



Tellurium 



Chromium 



Gold 



the follow- 

 , the prices 

 metal : — 



. S3,fi75 



2,695 



2,4.50 



. 2,450 



1,960 



... 1,102 



... 1,010 



... 1,040 



980 



560 



490 



490 



■300 



Gold, therefore, is not by any means the most precious of 

 metals, taking only the twenty-seventh place according to 

 this list, and, weight for weight, gallium commands a 

 price about two hundred and thirty times that of gold. 



Andr^e's system of steering balloons has recently been 

 tested by Mr. Perceval Spencer. A drag rope, five hundred 

 feet long and about one hundred pounds in weight, was 



Mr. Latimer Clark, f.r.s., whose death occurred on 

 Sunday, the 30th October, was a distinguished civil and 

 electrical engineer. Born at Great Marlow, in 1822, he 

 commenced a career of success as assistant engineer under 

 Robert Stephenson at the building of the Britannia and 

 Conway tubular bridges, an account of which he published 

 some years later. In the capacity of electrical engineer he 

 superintended the construction and laying of more than 

 one hundred thousand miles of submarine cable in various 

 parts of the world, and invented the Clark standard coil, 

 as well as numerous telegraphic improvements. A joint 

 paper by Mr. Clark and Sir Charles Bright, contributed to 

 the British Association in 1861, was the means of putting 

 electrical measurement on a firm basis. From suggestions 

 made in this paper, a committee, in which Lord Kelvin 

 was the leading spirit, evolved a rational system of elec- 

 trical units — the terms "volt," " ampere, ' " ohm," and so 

 on, being adopted as the result of their deliberations. Mr. 

 Clark was also the first to introduce the pneumatic system 

 of transmitting postal and telegraph matter. As fourth 

 president of the Society of Telegraph Engineers (now the 

 Institution of Electrical Engineers), in his inaugural 

 address in 1875 he gave a valuable account of the early 

 history of the electric telegraph. The deceased gentleman, 

 with Robert Sabine, was joint author of " Electrical Tables 

 and Formulae," a standard work, and, in collaboration 

 with the late Mr. Herbert Sadler, produced a book on 

 " Double Stars." He was also well known as the designer 

 of a cheap transit instrument, useful not merely as a model 

 for teaching purposes, but as a means of determining true 

 time. Mr. Clark was elected a Fellow of the Royal Society 

 in 1889, and he was also a Chevalier of the Legion of 

 Honour. 



