SCIENTIFIC NEWS. 



[June 1st, 1 8 



work the train by electricity. There is to be a complete 

 system of telephones, by means of which the attendants can 

 at any moment cause the train to be stopped if required. 

 We cannot help thinking that other precautions will be 

 necessarj^, especially to prevent overcrowding. 



W'm-m/i 



Fig. 3. — Section of Moving Platform. 



THE CHEMICAL SECTION AT THE MAN- 

 CHESTER EXHIBITION. 



NOT only from a local, but from a national point of view 

 the display of chemical products at this exhibition 

 is one of considerable importance. It brings vividly before 

 us the enormous strides made in the chemical industry, and 

 while reflecting that this great advance has been going on 

 quietly in obedience to the simple law of supply and 

 demand, we see that it involves not only a development of 

 chemical manufactures, but of the trades in which the 

 chemicals are used, and of the hundred-and-one aUied 

 branches of trade. A not unimportant benefit from this 

 great manufacturing progress, is also the employment it 

 gives to an immense number of men, women, and children 

 in our overstocked country. 



We refrain from mentioning in detail the exhibits in this 

 most instructive section, as this is already being done by 

 the technical journals, and we will content ourselves with 

 notes on some of the exhibits which are more generally 

 interesting. In the hygienic group there are several useful 

 antiseptic preparations, and a considerable number of well- 

 known disinfectants and deodorisers. Among the latter 

 are Jeyes' sanitary compound, which has just been 

 reported on by Professor Attfield, F.R.S., who has tested it 

 in dwellings, out-houses, drains, etc., and who says that it 

 answers as well as carbolic acid, while it is much cheaper, 

 and is perfectly miscible with water. He adds that a care- 

 fully conducted series of experiments showed that micro- 

 scopic germs, such as bacteria, bacilli, etc., were killed in a 

 few minutes, and in some cases instantly, by a five per 

 cent, mixture of the disinfectant with water, and very 

 quickly by a one per cent, solution. There is a very fine 

 display of coal-tar products used chiefly for dyeing fabrics, 

 and seeing that the first aniline dye (mauve) was discovered 

 by Dr. Perkin under thirty years ago, the great and 

 increasing development of this industry is very remarkable. 

 Great, however, as has been the advance in this branch of 

 manufactures, it will be well for us not to forget that 

 Germany has now outstripped us in the supply of these very 

 materials, which our chemists taught them to make. This 

 we referred to in our last number, and as this exhibition 

 affords proof of what can be done in England, we sincerely 

 trust that every effort will now be made on the part of our 

 manufacturers to recover their lost ground. 



A great development has also been made in the manu- 

 facture of pigments and paints. Artificial ultramarine, for 

 instance, is of comparatively late origin, and although it 

 is now used largely, up to about fifty years ago it was only 

 obtained in very small quantities from lapis lazuli by a 

 process of grinding and rinsing, which was at once tedious 

 and expensive. In the year 1824, a prize was offered in 

 France for the discovery of a chemical process for obtaining 

 artificial ultramarine, and in 1S28 it was awarded to 

 Gmelin, of Tubingen. About the same time a process was 

 also discovered by Guinet, of Toulouse. Ultramarine is now 

 manufactured in France, Germany, and England, and is 

 extensively used in paper making, calico printing, painting, 

 laundry work, etc. At the exhibition, Mr. Charles Scheu 

 not only shows excellent specimens of ultramarine colours 

 (blue, green, and violet), but he also shows a model furnace 

 lor manufacturing ultramarine, and a collection of the raw 

 materials used in the process. Messrs. Rawlins and Son 

 also show good specimens of ultramarine in various stages 

 of manufacture. This firm were the first to establish 

 works for making it in England, and from time to time 

 they have introduced important improvements in the pro- 

 cesses. Mr. Henry Crookes shows a heat-indicating paint, 

 which is a brilliant red, and has the property of gradually 

 becoming darker when heated, until at about 140° Fahr. it 

 assumes a dark brown colour ; on cooling it regains its 

 original tint. It is said that if this paint is applied to the 

 bearings of a machine or engine, it will act as a tell-tale ot 

 temperature, so that the attendant need not have to feel 

 them constantly with his hand. 



Many attempts have from time to time been made to 

 devise a non-poisonous substitute for ordinary white lead 

 paint, which often so injuriously affects the painters who 

 use it, and especially those who are engaged in its manu- 

 facture. The poisonous effects produced are believed to be 

 mainly due to the diffusion of the carbonate of lead in a 

 pulverulent form in the workshops, so that besides being 

 inhaled, it collects upon the hands, and is carried into the 

 mouth with the food. Ordinary white lead consists largely 

 of carbonate, which is readily acted upon by some of the 

 acid juices of the bod}', but sulphate of lead is practically 

 insoluble, and is supposed to be innocuous. Hitherto the 

 drawback to the use of sulphate as a paint has been that it 

 was too sticky, and could not be worked well with a brush. 

 About three years ago Messrs. J. B. Freeman and Co. intro- 

 duced a sulphate of lead paint of the density and consis- 

 tency required to take the place of ordinary white lead, and 

 were it not for the ignorance and consequent prejudice oi 

 workmen we believe it would be more largely used than it 

 now is. It has been favourably reported on by several 

 scientific authorities, it has the approval of the Government 

 inspectors, and its cost is about.the same as that of its more 

 dangerous rival. Messrs. Griffiths and Co. also show a non- 

 poisonous paint, but of a different kind. Theirs is made 

 from sulphide of zinc, which is said to be greatly superior 

 to the zinc-white, made from oxide of zinc. This firm also 

 has a fire-proof paint, which was adopted for the exhibition 

 building after being tested at the Owen's College. These 

 tests showed that it does not contain silicate of soda, or any- 

 thing that will cause an efflorescence, or make it crack or 

 peel. Messrs. Donald Macpherson show a kiosk made of 

 bricks covered with enamelled paint, also specimens of zinc, 

 wood, and stone coated in a similar manner, and to prove 

 that it will dry on a greasy surface they have actually 

 coated some tallow candles with it. Among the varnish 

 exhibits is a very noticeable one of Messrs. Ingham, Clark, 

 and Co. It consists chiefly of a collection of fossilised 

 resins and gums used in the manufacture of varnish, and 

 among them are beautiful specimens of gum amber from 



