HARDWICKE'S SCIENCE-GOSSIP. 



Ill 



consists of vitreous nicattcr formed wiiliin the great 

 volcanoes of the Miocene epoch ; and the melted 

 mass, slowly cooling, allowed the crystalline ele- 

 ments mixed with it to crystallize. According to 

 Dana, pitchstone is composed of albite or oligo- 

 close, rather than ortlioclose, that is, it contains 

 soda, or soda and lime, instead of potash : its 

 chemical constituents are silica, alumina, iron 

 lime, and soda. Porphyrine is an artiflcial produc- 

 tion, and is introduced here as an illustration of 

 the production of crystalline forms when molten 

 vitreous matter is allowed to cool slowly. This 

 substance is of a beautiful crimson colour, and is 

 said to be manufactured only in llussia, where it 

 is used for mosaic-work : its composition is 

 asserted to be a secret. As a microscopic object, 

 it appears to be little known, probably owing to its 



Fig. 73. Section of Porphyrine. 



scarcity : under the binocular, I know of few 

 objects that can compete with it. The beautiful 

 fern-like crystals embedded in the transparent 

 base would alone interest the observer; but, in 

 addition to this elegant outline, the fern-fronds are 

 of a beautiful crimson colour. The most effective 

 way of viewing them is with a two-thirds objective, 

 and Lieberkiihn. Many very beautiful crystalline 

 forms, adapted for microscopic observation, may 

 be produced by means of the blowpipe. The 

 following is the plan recommended by Mr. Sorby, 

 F.R.S. :— A small quantity of borax is mixed with 

 some mineral salt or oxide, and a little of it placed 

 in a small platinum ring of about one-eighth inch 

 diameter, and then fused with the blowpipe. After 

 fusing, the bead is to be kept for some little time 

 at a dull red lieat ; when cool, the ring containing 

 the bead may be cut off, and the whole mounted in 

 Canada balsam. The author advises the use of a 

 four-tenths objective for the examination of the 

 crystals. The following salts and oxides produce 

 beautiful crystalline forms :— borate of magnesia. 



zirconia, theolite (native tungstate of lime), mo- 

 lybdate of strontia, apatite, native phosphate of 

 lime. A full description and figures of the crystals 

 will be found iu vol. i. of the Monthhj Micro- 

 scopical Journal, p. 347. 



New Microscopical Journal. — We have 

 received the first number of a new journal of 

 natural history and microscopy, published iu Chi- 

 cago, under the name of The Lens. The principal 

 paper iu it, however, is taken from the Monthly 

 Microscopical Journal — illustrations as well. A 

 little leniency may be shown to this common trans- 

 atlantic fault, on account of the great fire. We 

 congratulate the editors ou so soon recovering the 

 loss then inflicted. 



On Staining Tissues. — It is desirable to stain 

 sections of all soft tissues, whether from healthy or 

 diseased specimens. Eirst, because it enables us 

 more accurately to distinguish germinal or nuclear 

 matter from formed material, or tissue proper, by 

 their differences in receptivity of colour ; and 

 secondly, because it brings into relief all consti- 

 tuents of soft tissue, and therefore renders their 

 study easier and more satisfactory. The staining 

 material which aids me most, and therefore suits 

 me best, is the alkaline solution of carmine made 

 after Beales's formula. The sections should be 

 placed in the carmine solution as soon as they are 

 made, and they should be made as soon as possible. 

 No positive rules can be laid down as to the precise 

 time required for the completion of the staining 

 process. It will vary, within certain limits, accord- 

 ing to the character of the tissue and alkalinity 

 of the solution. In regard to this latter point, I 

 may properly say that the carmine solution should 

 neither be neutral nor intensely alkaline : in the 

 former case, all portions of the tissue will probably 

 be stained alike ; in the latter case, much of the 

 younger or softer portion of the formed material sur- 

 rounding the germinal matter will be destroyed by 

 the excess of alkali. I generally permit my own sec- 

 tions to remain iu carmine for three or four hours. 

 Having completed the staining process, the sections 

 should next be immersed in a mixture composed of 

 Price's or Sarg's glycerine and distilled water, aa 

 3iv., acetic acid gtt. xx. This answers the double 

 purpose of rendering the so-called nuclei (germinal 

 matter, bioplast) sharp and clear, and of com- 

 mencing the process of impregnating with stron;^ 

 glycerine ; it will also remove the superfluous car- 

 mine. After being soaked in the glycerine an*', 

 water mixture for from twelve to twenty-four hours 

 they should be transferred to the following mixture : 

 purest and strongest glycerine, si-; P^n'c acetic 

 acid, gtt. V. They should be allowed to remain in 

 this mixture until they are fully saturated therewith. 

 This will take from two days to as many weeks. 

 — /. N. Banforth, 31. D., in the " Lens." 



