468 



NATURE 



\Sept. II, 1879 



The investigation was pursued further by producing artificial 

 irregulaiities in the pipe, and it then appeared that tlie more 

 completely the water could be thrown clear of the sides of the 

 pipe, the greater effect it produced in expelling the air and start- 

 ing the syphon. 



The author applied this and other principles in his intermittent 

 syphon, of which a working model was exhibited, and which 

 was illustrated by diagrams. Self-acting syphons have been 

 used in emptying vessels for measuring water, as in Osier's and 

 Bickley's self-recording rain-gauges ; and the syphon described 

 might be so employed and also in a more practical manner, such 

 as for flushing sewers by water which usually runs to waste. 



Mr. W. E. Ayrton read a paper by Dr. Muirhead On the 

 Constancy of the Capacity of Certain Accumulators, and a note 

 thereon by Mr. C. Hockin. The latter communication contained 

 an account of observations which were first begun with the object 

 of redetermining the capacity of certain condensers employed in 

 the testing of cables, and in terms of which the capacity of many 

 cables now submerged have been recorded and published. In 

 consequence of these papers a committee was appointed by the 

 Association, on the recommendation of Section A, for the 

 purpose of deciding upon an authoritative standard of electrical 

 capacity. 



Prof. G. Forbes made some remarks upon The Bursting of 

 Firearms, -when the AIuzzlc is closed with Earth, Snow, c^c. — 

 This well-known fact was explained in a simple manner. If the 

 charge moved slowly, of course very small pressure of air would 

 drive out the obstacle, which offered a very small resistance ; 

 but in practice the charge travelled with a speed of more than 

 the velocity of sound. The mathematical investigation showed 

 that the pressure generated with a plug of the density of air is 

 7i tons. The complete investigation is to be found in the Pro- 

 ceedings of the Royal Society of Edinburgh. 



The Section devoted Saturday as usual to the mathematical 

 papers, which were not so numerous as they have been in recent 

 years. 



Mr. H. M. Jeffery gave an account of his work On Plane Class 

 Culics with Three Single Foci, which concluded his enumeration 

 of curves of the third class ; and Mr. W. H. L. Russell com- 

 municated a theorem On Linear Differential Equations. 



Mr. y. W. L. Glaisher gave an account of Some Enumera- 

 tions of Primes of the Forms A,n -f I and 4« H- 3, referring to 

 the investigations of Prof. Tchebycheff, who had shown that 

 primes of the form 4« -t- 3 were more numerous than those of 

 the form 4« -h I, the difference in the numbers of primes of the 

 two forms up to a certain large limit x being for certain values 



of X of the order 



hjx 



Mr. Glaisher also communicated an 



elementary method of summing the series 



tan X -f tan 



-^ tan 



-I- &c., 



2 . 3 . . 



and similar series, and also some formulas in elliptic functions. 



Mr. A. J. C. Allen read a paper On some Problems in the 

 Conduction of Electricity, the principal object of which was to 

 solve the problem of the conduction of electricity in a spherical 

 current sheet, the electricity being introduced and carried off 

 from the sheet at any number of points, called electrodes ; and 

 also to do the same for certain finite portions of a spherical 

 sheet, bounded either by current or equipotential lines, the 

 motion being in all cases steady. This was effected by means of 

 a theorem, which was then applied to deducing solutions for a 

 number of finite areas on the sphere. The case of one source 

 and an equal sink on a complete sphere was discussed in detail, 

 and the current and equipotential lines shown to be two systems 

 of small circles. A similar theorem, though not quite so uni- 

 versal in its application, was shown to hold for a sheet in the shape 

 of a circular cylinder. The paper concludes with a solution in 

 singly infinite series of the problem of the conduction of electri- 

 city in a plane area, bounded by two concentric circles, and also 

 in that bounded by two concentric circles and two radii, meeting 



at an angle - (k integer). 

 « 



1. Carefully distilled sodium condensed in a capillary tube, 

 and placed in the retort, gives 20 volumes of hydrogen. 



2. Phosphorus carefully dried gives 70 volumes of gas, chiefly 

 hydrogen, which, however, is not PH3, although it gives some of 

 the lines of phosphorus. It is not PH3, because CUS04 is not 

 touched by it. 



3. Magnesium carefully prepared by Matthey is magnificent in 

 its colourings ; we get first hydrogen, then the D line [not sodium, 

 for the green line is absent], then the green lines of magnesium, 

 (i5) then blue line, then various mixtures of all of them, as the 

 temperature is increased, D being always the brightest, 2 volumes 

 (i cc) of hydrogen only were collected. 



4. With gallium and arsenic the pump always clicks, indicating 

 that no gas is given off. 



5. From sulphur and some of its compounds there is always 

 S02. 



6. From indium, hydrogen comes over before heatmg. 



7. Lithium gives 100 volumes of hydrogen. 



The conditions of the experiments have always been the same, 

 the only variable being the substance. The volumes stated are 

 those generally obtained ; almost all experiments are ended by 

 the cracking of the tube. 



On large Crystals of Mercury Sulphate, by Philip Braham. — 

 Mr. Braham exhibited crystals which had taken over two years 

 in forming, and were due to the presence of a trace of nitric acid 

 in the sulphuric acid in which they were formed. 



On the Manufacture of Crucible Steel, by Henry S. Bell, 

 F.C.S., &c. — The manufacture of crucible steel is one of the 

 most important industries connected with the town of Sheffield, 

 which boasts of not less than 1 20 firms engaged in the produc- 

 tion of this material. Notwithstanding the enormous output of 

 steel by the Bessemer and Siemens-Martin processes, this kind 

 of steel is unrivalled for the manufacture of the finer varieties of 

 cutlery and edged tools, &c. A brief outline of the process 

 itself is as follows :— The most of the iron employed for this 

 purpose is imported into this country in the shape of bars from 

 Sweden, where it has been smelted from very pure iron ores, in 

 a blast furnace, by the aid of charcoal, and subsequently puddled 

 to free it from impurities. 



The first operation to which it is subjected, is that knowii as 

 the cementation or converting process, the object of which is to 

 combine a certain quantity of carbon with the iron ; this opera- 

 tion is performed in a furnace of peculiar construction, where the 

 iron and charcoal are packed together in air-tight chests or 

 converting pots, subjected to a high temperature short of the 

 fusing point of iron, where it remains for a matter of three 

 weeks. 



After the conversion, when the pots are cold the bars are taken 

 out and found to be covered with blisters, hence it is termed 

 blister steel. In consequence of the various theories proposed to 

 account for this peculiar formation, the writer was induced to ; 

 make a series of investigations. For this purpose he was kindly j 

 furnished by Messrs. Seebohm and Dieckstahl, of the Danne- ' 

 mora Steel Works, with some samples of this blister steel, various 

 portions of which he submitted to analysis, the results of which 

 showed a marked increase of silicon where the blisters occurred. 

 On inspecting one of these bars of blister steel, it is found that 

 it has undergone both a physical and a chemical change. 



The iron has now assumed a crystalline structure, and has 

 chemically combined with a certain amount of carbon. This 

 latter change commences on the exterior, and extends itself to 

 the interior of the bar, if the process be continued sufficiently 

 long, thus showing that carbonic oxide never penetrates into the 

 centre of the bar, until the whole is converted into steel. 



The writer is indebted to the kindness of the above-mentioned 



firm for a sample of bar iron, before and after conversion, m 



order to ascertain the exact chemical change that took place 



during the process. The following are the results obtained :— 



Before Conversion After Conversion 



SECTION B— Chemical Science 

 Notes on Recent Spectral Observations, by J. N. Lockyer, 

 F.R.S. — The following results have been obtained by the 

 method recently described to the Royal Society {Proc. R.S., vol. 

 xxix. p. 266 : — 



t 



Fe 

 C ... 



Si... 

 S ... 

 P .., 

 Mu 



99-471 

 0-352 

 0-050 

 0027 



0'025 



0-075 



98-603 

 1-250 

 0-035 



0-022 

 0-018 

 0-072 



lOO'OOO 



lOO'OOO 



The decrease in impurities appears greater than it really is, 

 owing to the fact that the bar itself has increased in weight by the 

 addition of carbon. 



