November, 20, 1914. THE COLLIERY GUARDIAN. 1075 ____________________________________________________________________________________________________ LETTERS TO THE EDITORS. _________________________________________ ______________ The • Editors are not responsible either for the statements made, or the opinions expressed by correspondents. All communications must be authenticated by the name and address of the sender, whether for publication or not. No notice can be taken of anonymous communications. As replies to questions are only given by way of published answers to correspondents, and not by letter, stamped addressed envelopes are not required to be sent. ELECTRIC LAMPS COMPARED WITH OIL LAMPS. Sirs,—On my return from abroad I have had brought before my notice the letter signed by “ Practicus,” and which appeared in your journal of October 16. I should be very much obliged if Mr. John George (who is acting as agent for the Ceag Company) will state whether or not he is the author of, or had a hand in, the letter signed ‘ ‘ Practicus ”; as there seems to be so much to indicate that this letter is from the same source as a somewhat similar letter by Mr. John George, in which he signed himself as “ A Colliery Manager. ” For the benefit of the few who might think that the letter by “ Practicus ” was from a disinterested party, I think your readers are entitled to know whether or, not Mr. John George and “ Practicus ” are the self- same person. If my surmise is correct, I do not think that there is any need for me to reply to the other matters mentioned in the letter by “ Practicus,” as they are so obviously ! biassed, and so clearly indicate their origin as being from an electric lamp maker’s representative. As regards the two cases referred to in my paper; having received the information privately, I was not at liberty to mention the names of the collieries; but I may say that one of the cases was at a colliery not very far distant from the Scotch colliery where the fatal accident happened about a week ago, and in connection with which it is stated that a miner was found dead, and our lamp alongside him with the light extinguished, but his electric lamp was alight, and it is well known that great difficulty and risk was experienced in recover- ing the dead man’s body; so that perhaps this additional concrete instance will satisfy “ Practicus ” of the pro- bable truth of my statement, and the correctness of the theory advanced, that it is better that the man, in his ordinary work, should only use a light which in the presence of dangerous gases will be so affected that he is absolutely compelled to clear out from the dangerous district. As to the lecture carrying more weight if it had been delivered by an independent expert, the writer would willingly have stood aside had some expert come for- ; ward, but as the experiments and the apparatus con- nected therewith involved a considerable outlay of ■ money, this may have possibly deterred other experi- . menters or other lamp makers from attempting such experiments. Furthermore, for a great many years, we have adopted the policy of spending a reasonable por- tion of our income in research and experimental work, and whilst we are naturally sorry if the results have hurt the feelings of “ Practicus ” and other electric lamp makers, we have the satisfaction of knowing we have done some little to substantiate the claims of the miner’s flame lamp, and if the “ paper ” is the means of inducing other experimenters to continue investiga- tions on the interesting subject touched upon in the “ paper,” I shall feel repaid for my trouble, in spite of the strong language of “ Practicus.” As regards the experiments being ” scientific piffle,” that class of argument is characteristic of “ Practicus,” and scarcely calls for reply, excepting to say that the “ paper ” records actual experiments carried out, and certainly does show that it is a much more difficult matter to get an explosion out of a miner’s oil safety lamp than was hitherto thought to be the case. Most of the experiments have been repeated before mining teachers and mining classes who have visited our works; the latest occasion being on Saturday last, when about 30 Rothwell adult mining students and their teacher witnessed’ the experiments and the weight dropping test, glass breaking test, and explosion from electric lamp. If “ Practicus ” will take the trouble of reading through the “ paper ” he will find that I do record an actual ignition of gas with a Ceag electric lamp! As regards the colliery having 1,400 electric lamps, in which 100 have been holed with a pick during the last 18 months, it may interest “ Practicus ” to know that the lampman estimates that he has not had this quantity of flame lamps similarly holed in the previous 18 years, and accounts for the large quantity of electric lamps being so holed from the fact of the light gradu- ally dimming down; the colliers then draw the lamps nearer and nearer to the coal face in order to see their work, until finally the lamps get within reach of the pick. In other instances the men place the electric lamps in positions where they could not put oil lamps; in these positions the electric lamp is more subject to being struck. E. A. Hailwood. Morley, near Leeds, November 17, 1914. _________________________ COLLOID SILICA IN SHALE. Sirs,—The writer is unable to find proof of the very definite statement contained in your leader of October 30, that the quartz granules in Altofts shale ” are ” enclosed in an envelope of colloid silica, by which it can be ascribed to Dr. Mellor, and it is con- sidered that if the matter were referred to that scientist direct, it would be repudiated. Certainly there is some mention of this in a report on Altofts shale by Dr. Mellor appended to the Fifth Report of the Experimenting Committee, but, as the afore- mentioned scientist says therein, the views thereon are speculative. You will agree that there is a great difference between “ may be ” and “ is.” But assuming it be correct, of which it is more than doubtful, as this colloid envelope would be soluble, what protection can it be against the underlying insoluble granule? During the course of his career, the writer has taken many hundreds of quinine capsules coated with gelatine, which is a colloid, but it has never before occurred to him that it may be suggested that such an envelope ot coating would be a permanent preventative of the drug acting, and certainly the writer never found it so. In your leader you say that Altofts shale has not been found to possess harmful properties in the least degree. The writer was once informed that to find any- thing it must be searched for. Of course, the converse is that if you don’t want to find a thing, don’t seek for it. Still the writer, without seeking, was informed during the last few days of two cases of men, who were working on the roads, giving up their work owing to the effect of the dust. The dust in question has about the same amounts of free and colloid silica as the Altofts shale. Therefore, it would be interesting to have a little more detail upon the alleged observed immunity from harmful influences exhibited by this dust. On treating crystalline quartz (sand) with boiling alkaline solution, and evaporating, the writer obtained a silicate of the alkali used. It would, therefore, be interesting if you will explain exactly how this artificial ' envelope of colloid silica was obtained. E. O. SlMCOCK. Hanley, Staffs. November 18, 1914. _______ [As the writer of the above letter may not have read the remarks made in the report of the Royal Commis- sion on Metalliferous Mines and Quarries upon this subject, we reproduce that portion dealing with the question of colloid silica. [Second Report, pp. 145-6.] The injurious qualities of free crystalline silica led us to enquire whether the presence of this material can be readily and certainly ascertained, thus enabling the dangerous nature of a given dust to be determined. The difficulties, however, which surround the chemistry of the compounds of silicon raised a fresh problem, and we sought aid from Dr. Mellor, who, from his experience of the pottery industry at the County Experimental Laboratory, Stoke-on-Trent, possesses special knowledge of the subject. Dr. Mellor told us that after careful research he had established a method (24,691), by which the amount of quartz present in material contain- ing other forms of silicon can be estimated to within 2 per cent.; but he drew our attention to the existence in certain rocks, for example, in Altofts shale, of granules of quartz enclosed in an envelope of colloid (non-crystalline) silica (24,695). The dust of Altofts shale has not been found to be injurious either from experience of its effects upon those exposed to its inhalation or from laboratory experiments carried out by Prof. Beattie. We are unable to say whether this combined form of colloid and crystalline silica frequently occurs in nature, but in any case it can be distinguished from ordinary quartz by the property the colloid film pos- sesses of taking up stains such as red ink. Pure crystalline silica does not stain in this way. Why it is that pure crystalline silica dust such .as is used in the Potteries, and found in the dust of grindstones at Sheffield, is so dangerous in its effects, while other dusts, such as Altofts shale, which contain free silica, seem practically innocuous, has not been determined. Under the microscope the crushed silica used in saggar packing in making porcelain, and the sharp silica crystals to which the abrading power of grindstones is due, appear different from the granules of silica found in the shales, which seem more rounded. The difference is analo- gous apparently to the difference between what is known as ” sharp sand ” used for abrading glass and other substances, and the rounded sand found at Pegwell Bay and other places, which has been so worn into tiny spheroids by the action of the sea that it can be actually used for burnishing gold on pottery which “ sharp sand ” would immediately scrape off. Whether the comparatively innocuous character of some kinds of finely divided silica is due’to spheroidal form or to the colloidal coating referred to above remains an unsolved problem. An effort at solution has been made, but without definitely settling the question. Animals were exposed by Prof. Beattie to dust composed of sharp pounded silica pre- viously boiled in alkali for 100 hours by Dr. Wheeler, of the Home Office Experimental Station at Eskmeals, in order to render the surface of the particles colloidal; the lungs of these animals showed injurious effects, though only after a considerably longer exposure to this dust than after exposure to the dust of free crystalline silica.- Whatever be the solu- tion of the problem, we are, however, convinced that the dust of free crystalline silica is responsible for an excessive phthisis death rate among men exposed to its inhalation. Our knowledge on this question is at present very fragmen- tary and defective, and in view of the great importance of the subject, in the administration both of the Factory Acts and Mines Acts, we strongly recommend that it should be further investigated. Eds., C.G.] __________________________ Amongst the sheriffs nominated for the counties of England and Wales are the following:—Monmouthshire: W. R. Lysaght, Castleford, Chepstow, of the well-known Newport firm of ironmasters; Glamorgan: E. L. Evan- Thomas, chairman of the East Indian Coal Company and a director of North's Navigation Collieries; Montgomery- shire : J. B. Williams, of Dolforgan, a director of the Great Wyrley Colliery Limited ; Cheshire: Col. W. L. Pilkington, of Norley Bank, Frodsham, a director of the St. Helens Collieries Company Limited; Durham : Sir A. M. Palmer, Bart., of Walworth Castle, Darlington, a director of Messrs. John Bowes and Partners Limited, and chairman of the Widdrington Coal Company Limited, THE BY-PRODUCTS TRADE. Tar Products.—The market is steady, and prices are fairly well maintained all round. Carbolics are firm and dearer, and toluol likewise distinctly favours sellers. Benzols remain unchanged. Naphthas are much about the same, which is satisfactory considering the fall in the exports. Creosote unchanged. Closing values are:— Benzols.................................... /101 Do. North.............................. /8|to/9 Toluol ....................................1/10 to 1/11 Carbolic acid, crude (60 per cent.) .......... 2/7 to 2/8 ...................... Do. crystals (40 per cent.) ........ /11| Solvent naphtha (as in quality and package)... /9 Crude ditto (in bulk) ......................... /5i Creosote (for ordinary qualities) ............ /3-j^j Pitch (f.o.b. east coast) .................... — Do. (f.a.s. west coast) .................... — Tar (liquids in 1 ton) ......................15/9 to 17/3 [Benzols, toluol, creosote, solvent naphtha, carbolic acids, usually casks included unless otherwise stated, free on rails at maker's works or usual United Kingdom ports, net. Pitch f.o.b. net.] Sulphate of Ammonia.—Things are rather quiet, and every effort is being made by intending buyers to depreciate the market as much as possible by paring half-crowns off quotations which are not backed by sufficient business to give them more than paper value. The forward market is very quiet. Nearest prompt values are :— London (ordinary makes) .......... ^£10/5/ Beckton .......................... <£10 Liverpool ........................ <£10/15/ to £10/17/6 Hull.............................. £10/12/6 Middlesbrough.................... £10/13/9 ...................... Scotch ports .............................. £11 Nitrate of soda (ordinary) per cwt. ... 9/9 [Sulphate of ammonia, f.o.b. in bags, less 2| per cent, dis- count; 24 per cent, ammonia, good grey quality; allowance for refraction, nothing for excess.] ______ Trade Notes. Hostilities have led to attention being paid by Russia to the nitrate of soda deposits in Central Asia, of which there are several, though of comparatively small magnitude com- pared with the Chilean sources. It is evident that the general state of the chemical and allied products trade is fairly normal, if the Board of Trade returns for October are to be relied on. Still, as far as coal tar by-products are concerned, the exports show decreases all round, with the exception of tar; but as this heading also covers crude, refined, and tar varnishes, it is not much to go by. Pitch shows up worst, and benzols also are short by about £4,500. Yet in the aggregate the net loss is less than might have been expected, viz., £4,000, which is due to the exports of aniline oil and toluidine, which rose from £2,710 last year to £12,664 in October of thig year. Sulphate of ammonia shows a loss on the month of October of 4,800 tons. As contributors to this decline, Japan and U.S.A, take the first and second places. Dutch East Indies, however, took about four times more than last year. Spain remained almost stationary. France and Germany between them only accounted for a decline of 1,000 tons, whereas Japan alone took 7,700 tons less. Phosphates are always of interest in connection with sul- phate of ammonia, as anything that cheapens the production of soluble phosphates from phosphatic rock helps to encourage the use of sulphate of ammonia. Tennessee rock operators have been experimenting with a new process of producing a really high-grade superphosphate, which owing to its superior qualities will be sold under new and advan- tageous guarantees favouring the user. Up to now details of the process have been kept secret, but the plant erected was to start operations last September. Whatever opinion may be, facts go to prove that there are those among British coal and tar by-product producers who think the time is ripe for extensions and new developments. The Southport Town Council have accepted a tender for the erection of a tar distilling plant. Also steps are reported in the Doncaster district in the direction of extracting oils, motor spirit, and a smokeless fuel from coal, while the tar fractions will also be turned to account in various ways. The remarks made last week concerning the difference between trying to resuscitate the aniline dye industry in this country and producing coal tar products, or the associated by-product arising from the various methods of coking or distilling coal, are strikingly confirmed by the slow progress the advisory committee of the Board of Trade is making; and also in some of the criticisms that its tardiness have provoked. Still all the blame does not lie with the Customs authorities, who are inclined to be dense and unsympathetic over the matter of duty-free industrial alcohol. There are good reasons foi some of this apparent apathy on the part of the authorities. The writer recollects a case in which an Excise officer once distinguished himself by condemning a gas liquor still for the distillation of ammonia as an illicit still because it might be used to distil alcohol, because it was a modification of the Coffy still, and the saturator was a potential dephlegmator and condenser, although it was full of warm acid, and the sulphate of ammonia was salting out freely; while the still itself reeked of cyanides. The officer lost the day in court, but those responsible for diffi5 culties in granting the use of dutv-free alcohol even for research work must not be measured by the same standard as this Excise officer. If the use of free alcohol, in every possible industrial way, were granted to-morrow, the aniline dye industry would not show very marked progress in Great Britain, even in the next 12 months. Last week the imports of pitch were 65 casks, 301 drums (from U.S.A.), and 81 bags. Tar was 100 barrels. The exports, however, were 5,800 tons of pitch, and 33.280 galls, of tar, in addition to £86 worth. Exports of sulphate of ammonia amounted to 5,740 tons, mostly to Java and Dutch East Indies. Spain showed an improvement, while some went again to Rotterdam. ____________________________ Mr. F. G. Randall has relinquished the position of superintendent of the line of the Great Eastern Railway Company. Mr. William C. May has been appointed chief traffic manager, with control of the passenger and goods departments. Mr. Harry Jones has retired from the position of chief engineer of the company, and will be succeeded by Mr. H. Wilmer.