266 



SCIENCE. 



[N. S. Vol. IV. No. 87. 



sten steel, and their orifices are given the form 

 of the proposed section of the bar to be made. 

 They are carried in a holder which permits 

 their convenient introduction and removal for 

 substitution of one form for another. Before 

 the operation begins, the ' container ' is set ver- 

 tically to receive the charge, and the dies and 

 holder are heated, also, to prevent chilling. 

 Once charged, the container is turned into 

 the horizontal position, and the plunger of a 

 hydraulic press, working under about two tons 

 per square inch pressure, is forced into the con- 

 tainer, driving the plastic metal out through the 

 die, from which the bar issues of the desired 

 sectional shape. 



The preliminary heating is effected by gas- 

 burners, and the operation of the apparatus 

 keeps up its temperature to the required point 

 until its working hours are over. The appara- 

 tus in use at the works of Mr. Dick, the Delta 

 Metal Co. , London, has a cylinder of about two 

 feet external diameter and an inner liner five 

 or six inches. The product is about fifty 

 charges per day, and the cost of operation is 

 claimed to be small, the wages of two men and 

 a boy. The metal so produced is claimed to 

 have greatly increased strength, as compared 

 with that made by simple casting, in the usual 

 manner, precisely as ' Whitworth steel ' is im- 

 proved by pressure. Common yellow brass 

 gains about 24 per cent, in tenacity. ' Delta 

 metal' bars thus made are reported to have 

 a tenacity of 48 tons per square inch as against 

 its former strength, 32 tons, and to exhibit a 

 ductility of 32.5 per cent, as against 20 per 

 cent. 



Only the copper-tin-zinc alloys and similar 

 metals have, as yet, been treated ; but the in- 

 ventor proposes ultimately to employ the pro- 

 cess in the manufacture of iron and steel bars 

 of difficult sections. 



THE SANITARY VALUE OP SUNLIGHT. 



At the Annual Congress of the British Institute 

 of Public Health, which was held at Glasgow, 

 from July 23d to July 29th, Professor Ramsay, 

 of University College, London, in his address as 

 President of the Chemistry and Engineering 

 Section, dwelt on the sanitary value of sunlight. 

 According to the report in the British Medical 



Journal, he said that the most common evidence 

 of the activity of the violet and ultra-violet rays 

 is sunburn, which is probably due to the effort 

 of the surface cells to protect themselves against 

 these rays by secreting a pigment which can 

 absorb them, and the peeling which accompan- 

 ies severe sunburn is merely the shedding of 

 such dead cells as have been unable sufliciently 

 to protect themselves. The Rontgen rays are 

 particularly apt to cause the worst kind of sun- 

 burn, in one case causing the finger nails of a 

 hand which had been repeatedly subjected to 

 them to come oflf. Professor Ramsay drew at- 

 tention to the well-known researches of Profes- 

 sor Marshall Ward, in which he found the violet 

 and ultra-violet rays of the sun, or even of elec- 

 tric light, to be capable of disinfecting the 

 bacilli of typhoid and anthrax. The same sub- 

 ject has now been investigated from the chem- 

 ical side by Dr. Arthur Richardson. Dr. Rich- 

 ardson determined the circumstances which 

 caused the fading of certain water colors when 

 exposed to light, and examined the action of 

 light on carbon compounds and urine. He 

 found that the effective agent in bringing about 

 the changes which he observed is peroxide of 

 hydrogen. When certain organic materials, 

 such as carbolic acid, and some alcohols, or 

 oxalic acid, are exposed in a damp state to sun- 

 light, hydrogen peroxide is produced. Two 

 quantities of fresh urine were tested for hydro- 

 gen peroxide ; none was found. One was then 

 exposed for six days to sunlight; the other was 

 kept in the shade. The exposed sample was 

 clear and was found to contain peroxide, while 

 the portion kept in darkness swarmed with 

 bacteria, had grown foul and contained no 

 peroxide. Even after 23 days' exposure to sun- 

 light the one showed no putrefactive change, 

 while the other was entirely putrefied. Similar 

 experiment was made where one sample was 

 shaded with ruby glass, decomposition and 

 absence of peroxide ensuing, while the portion 

 exposed to sunshine was quite unaltered in ap- 

 pearance. Some of the sunned samples, after 

 they had developed a considerable quantity of 

 peroxide, were kept in the shade, but immedi- 

 ately developed fungoid growths, and the per- 

 oxide disappeared. Further experiment showed 

 that the presence of oxygen was necessary for 



