i6o 



HARDWICKE'S SCIENCE-GOSSIP. 



the matrix cannot be ground sufficiently thin to be 

 transparent, which amourts to saying ordinary coal 

 cannot be sectionised. The loose friable lamince 

 easily show vegetable remains, but then these are not 

 sections. Mr. Walker says he has some very fine 

 coal sections, but he has evidently only got coal 

 " nodule sections," a very different thing. He 

 breaks the nodule and then cuts sections of the 

 contained fossil-wood. This is not coal. Mr. Harris 

 has succeeded in obtaining one slide which shows 

 structure and is a good example. I should certainly 

 like a little more information with regard to this one. 

 Is it transparent ? Is it anything more than a section 

 of contained fossil-wood? Mr. Griffith informs us 

 that Professor Henfrey cut hundreds of sections in 

 the manner referred to, but then Mr. Griffith says it 

 is coal of a lignite character which is to be used for 

 this process. Now the question raised is whether 

 ordinary coal can be cut into transparent sections, 

 not whether lignite can be so cut, and i\Ir. Griffith in 

 common with the other correspondents implies that 

 it cannot, by telling us it is a particular kind only, 

 which I think I am justified in saying is not true coal 

 at all. I should like to ask Mr. Griffith to withdraw 

 this potash and acid process from the next edition of 

 the "Micrographic Dictionary,",' and add to it the 

 necessary addition that it applies to lignite instead of 

 coal. Your correspondents fully j ustify my statement 

 that transparent sections of ordinary coal cannot be 

 made by the potash and acid or any other known 

 process ; that no such sections exist ; and they add to 

 it that they would show no structure if made, which 

 I fully believe. — E. Holmes. 



Cutting Sections of Coal. — Mr. C. H. Griffith 

 has, no doubt, been still more highly amused with the 

 continued success of the " Micrographic Dictionary's " 

 practical joke. His " sapient student " who endea- 

 voured to soften a nail (query, by soaking in a solution 

 of carbonate of potash ?) will no doubt be pleased to 

 find so many other sapient individuals to keep him in 

 countenance. As, perhaps, some of the readeis of 

 Science-Gossip may not be sapient enough to see the 

 point of the joke, I quote the *' Micrographic Dic- 

 tionary " — it gives three methods of preparing coal for 

 microscopic examination. I. Grinding to powder; 2. 

 Maceration ; 3. " Macerating the coal for about a week 

 in a solution of carbonate of potash, at the end of 

 that time it is possible to cut tolerably thin sections 

 with a razor." (Also see " Carpenter," last edition), 

 (nothing is said about digesting with heat). Mr. 

 Griffith now tells us that lignite, and not coal, is the 

 material to be operated upon. The fact is, this is one 

 of the numerous inaccuracies that disfigure an other- 

 wise useful work. If your correspondent refers to 

 " Entdeckung neuer pflanzlichen Gebilde in der 

 Steinkohle und im Anthracit. P. F. Reinsch," and 

 " Neuere Untersuchungen iiber die Mikrostruktur der 

 Steinkohle des Carbon der Dyas und Trias " (by the 



same author), Erlangen, 1S81, he will find that coal is 

 not so devoid of interest as he imagines. — F. Kitton. 



On the Continuous Observation of Minute 

 Animalcula. — The animalcula on which I tried 

 the experiment of sealing hermetically in a small 

 quantity of water with enclosed air, are some of them 

 alive and active at the end of five weeks.- — E. H. 



Mounting Entomostraca. — Will some of your 

 numerous readers inform me how to mount the 

 Entomostraca, such as Daphnia, Cyclops, Canthi- 

 camptus, Diaptomus, Cypris, &c. , and in what 

 mediums? I have consulted Carpenter, Hogg, Davis 

 and others, but can find no directions sufficient for 

 my purpose ; even Baird says nothing upon the 

 subject. Also I should be glad to know what would 

 dissolve them out of their shells, so that their outer 

 cases also may be preserved for mounting or drawing, 

 as it is difficult to obtain the shells clean from mud, 

 debris, and parts of the bodies. In return, I would 

 beg to inform your readers that at a small pond in 

 the grass-field quite close to the farm-house at 

 Quinton Hill, Waltham Abbey, a stone's throw from 

 the road from Waltham to Sewardstone, I found on 

 the 5th of this month (May) quantities of the male 

 of Daphnia pitkx ; they cannot be missed or mistaken 

 as the superior antennee are so different from any 

 others of the tribe. — R. T. Aiidrnvs. 



^ Micro-Tanks,— I find the best to be crystallised ' 

 dishes of about seven inches diameter. They only cost 

 about id. each, and I have kept objects in them for 

 about twelve months. I have them on American 

 flower-pot brackets screwed to the sides of a north 

 window one above another. — John Alex. Ollard, 

 F.R.M.S., Enfield. 



The Quekett Microscopical Club. — The 

 March number of the Journal of this club has papers 

 on "Fluid contents in Meteorites," by Heinrich 

 Hensoldt ; " The Injection of Specimens for Micro- 

 scopical Examination," by Mr. T. Charters White 

 (president); "The Structure and Division of the 

 Vegetable Cell," by Mr. W. H. Gilbert ; and on an 

 " Improved Compressorium," by Mr. J. D. Hardy. 



Manchester Microscopical Society. — The 

 annual Report of this society (President, Mr. Thomas 

 Brittain, F.R.M.S.), shows a very healthy and vigorous 

 activity. Some of the best papers read have already 

 appeared in the "Northern Microscopist." 



Hackney Microscopical Society.— The fifth 

 annual Report of th is Society is published, and contain 

 the Address of the President, Dr. M. C. Cooke, and a 

 capital paper by Mr. J. E. Greenhill, on " Pre-historic 

 Hackney." 



"Studies in Microscopical Science."— This 

 serial work has improved on the first number, and 

 promises to be one of high value to actual workers 

 and earnest students devoted to histological research. 



