BARDWICKE'S SCIENCE-G OSSJJ^. 



Oi 



ceivable. Some of the loose friable matter between 

 the laminae of ordinary house-coal I once prepared 

 by steeping for some days in liquor potassae, and then 

 mounting in balsam. In a few weeks, the additional 

 transparency acquired from the balsam, rendered 

 coniferous structure observable here and there on the 

 slide. It was too friable to cut or grind, so I merely 

 took the thinnest bit I could get. I do not know 

 whether the liquor potassae had any action on it or 

 not. — C. L. Lord. 



Sections of Coal. — In your April number of 

 Science-Gossip there appears an article by F. 

 Kitton giving his experience on coal, and asking for 

 the experience of others who may have tried the 

 same. I cannot say that I have waited over a year for 

 the coal to soften, but I have some veiy fine speci- 

 mens of coal sections, showing distinctly the woody 

 tissue, dotted ducts, scalariform vessels of ferns, and 

 one slide showing sporangia. Now I take it for 

 granted that those who wish to make sections of coal 

 for microscopical examination, wish to show the vege- 

 table origin of coal, so I will relate my experience. 

 1 find among the soft coal that is used in this state, 

 i.e. Iowa coal, some hard heads, so called (that is, 

 hard lumps of coal in various stages of transilion from 

 good coal to charcoal), and well-preserved wood 

 mixed with sulphide of iron. I break up these 

 lumps and cut oat with a cliisel the wood from the 

 coal, which is in every respect (for our purpose) the 

 same as the coal without the bitumen ; now by break- 

 ing this in the proper direction I am able to get sec- 

 tions both ways of the tissue, and when ground down 

 thin make a good transparent object, or opaque by 

 shutting off the light from the mirror, and using the 

 condenser, when the sulphide of iron glistens like 

 gold dust among the woody tissue. Such is my exper- 

 ience, and 1 think the best way to obtain good speci- 

 mens of woody tissue from coal ; but I hope that 

 some others of your readers will kindly state their 

 experience as Mr. F. Kitton suggests, and if this is 

 new to, or will help any of your readers I shall be 

 glad that I have contributed my mite. — John Walker, 

 South Minneapolis, Min?iesota, U. S. A. 



Cutting Sections of Coal.— In the April No. 

 of " Science-Gossip," Mr. F. Kitton calls attention 

 to the directions given in the " Micrographic 

 Dictionary " and other works, for the cutting of thin 

 sections of coal. During the years 1878-9, I many 

 times tried to cut a section, and like your correspon- 

 dent, all my attempts ended in failure. I have soaked 

 pieces of coal in a strong solution of bicarbonate of 

 potash, and on examining them at the expiration of a 

 fortnight I found no change. I replaced them in the 

 solution and kept them covered for several months, 

 and although I examined them at frequent intervals, 

 I never could obtain a section, in fact they were as 

 Lard as when they were first placed in the solution. 



On one occasion I boiled some pieces of coal in the 

 solution for a couple of hours, and when I attempted 

 to cut It, I found the coal was a little softer on the 

 surface, but too brittle to obtain a section.^y. Wilson. 



Sections of Coal. — After many years' experience 

 the results obtained with ordinary marketable coal 

 of Great Britain (;annel coal excepted) are not suffi- 

 ciently good to repay the time occupied in their 

 production. Having been intimately connected with 

 the production of coal, I have endeavoured to gain 

 all the information I possibly could respecting its 

 structure and mode of formation from sections of 

 my own preparing, knowing full well that any fossil 

 wood with indistinct structure is passed off as coal by 

 dealers to the unwary. I have tried repeatedly to 

 get a good slide of ordinary coal, and the outcome of 

 all my labour is one section only that shows any 

 structure, and this was cut fiom a piece of ordinary 

 marketable coal raised at Illinois, U.S.A., and is a 

 good example of both formation of co.al and preserva- 

 tion of structure of the wood composing same. The 

 method I adopted in procuring this section was as 

 follows. I cut a piece about a quarter of an inch in 

 thickness with a fret saw, placed it in pure turpentine 

 for some considerable time, then in dilute Canada 

 balsam, allowing the coal to remain in this until I 

 thought it was saturated. I then allowed the turpentine 

 to evaporate, and by a gentle application of heat grad- 

 ually hardened the balsam the section had absorbed. 

 One side was then ground fiat, polished and cemented 

 to the slide the section was to occupy ; when com- 

 pleted the other side was a simple repetition of careful 

 grinding on a water of Ayr-stone, just as an ordinary 

 rock section would be treated, only with more care 

 when the critical point was approached. I honestly 

 believe chemicals and razors the greatest fallacies for 

 doing the work I have described, and it is a great pity 

 new editions of good works are disfigured with 

 such errors. — W. H. Harris, Fly mouth. 



Cutting Sections of Coal.— I am greatly 

 amused at the discussion which has arisen in your 

 columns anent the cutting of coal sections. I suspect 

 your correspondents have been experimenting with 

 the refractory anthracite coal too common in our 

 coal scuttles I but this being nearly all mineral 

 matter, of course, does not yield to the action of 

 the potash. Neither would it show much if so cut ; 

 they remind me of a former sapient microscope 

 pupil of mine, who took to himself much credit for 

 soaking a nail from the "Victory," in the hope 

 of making a section of it for the microscope to show 

 the structure. The coal for which this process is 

 recommended, and which yields the best objects, is 

 that which is more of a lignite character, and when 

 so treated and digested with heat, is cut readily. To 

 my own knowledge Professor Henfrey cut hundreds 

 of sections in this manner. — Cha:. II. Gnffitk. 



