HA RD WICKE'S S CIENCE- G OS SIP. 



*59 



macere was considered by the earlier observers to be 

 a simple coloured material, to which Naegeli gave the 

 name Diatomine. More recent observations have 

 determined that this material (Endochrome) is not the 

 simple, coloured matter it was at first supposed to 

 be, and for those of our readers who may be desirous 

 of investigating this substance the following directions, 

 extracted from the above paper, will be of service. 

 In order to obtain it pure it is necessary that the 

 diatoms should be quite free from other Algce, and if 

 marine, should be many times washed with fresh 

 water, and lastly in distilled water, filtered and dried 

 rapidly on the filtering paper. The diatoms thus 

 prepared are then placed in a sufficient quantity 

 > if alcohol of 90° strength to cover them and left (pro- 

 tected from the light) to macerate. After being a short 

 time in the alcohol they become a very decided green, 

 and the alcohol appears of a golden yellow colour. 

 After six to eight days the alcohol assumes a dark 

 green, with a more or less brown tinge, and the 

 diatoms will have lost a greater part of their colour ; 

 but it requires about a month to deprive the plasm 

 entirely of its colour. The alcohol after eight days 

 should be filtered, and we now obtain a concentrated 

 alcoholic solution of the pigment. In order to obtain 

 the two principal colouring-matters of which Diato- 

 mine is composed, M. Petit employs the following 

 method. The diatoms are to be macerated in alcohol 

 as before described ; he then adds to the filtered solu- 

 tion sufficient distilled water to reduce its strength to 

 36 ; he now adds chloroform equal to \ of the entire 

 volume. After agitating the mixture for a minute or 

 two, it is allowed to settle. After some hours the 

 separation is complete ; the chloroform has taken up all 

 the green colouring matter (chlorophyl), and has sunk 

 to the bottom of the tube or vial, whilst the yellow 

 (phycoxanthine) being more soluble in the weak 

 alcohol, floats on the surface. After decantation he 

 washes a second time in chloroform, and proceeds as 

 before. Ordinarily this second washing suffices to re- 

 move all the chlorophyl. If the supernatant part is not 

 clear, add a few drops of 90 alcohol, which will 

 render it transparent. We now have the two princi- 

 cipals isolated, and by evaporating the solutions we 

 can obtain them in solid state. The green matter 

 (chlorophyl) possesses a vinous red fluorescence by 

 transmitted light ; it is of an emerald green, but the 

 colour is_always more or less dark. MM. Kraus and 

 Millardet say that this green principal is in no degree 

 different from the chlorophyl of the larger plants. 

 The yellow matter (phycoxanthine) has a brick -red 

 fluorescence, but less intense than that of diatomine ; by 

 transmitted light it is of a beautiful golden yellow, but 

 which soon disappears even in diffused light. — F. A". 



Highbury Microscopical and Scientific 

 Society. — The syllabus of this society for 1880 

 includes papers on "The Skin and Hair," "Micro- 

 scopic Sections of Rocks," "Collecting Microscopic 



Objects," "Missing Links," &c. The conversazione, 

 which was very successful, was held on June 10. 

 The following are the officers : President, Frederick 

 Fitch, F.R.M.S., Hon. Sec. B. H. Woodward. 



Deutzia SCABRA. — The exquisite beauty of this leaf 

 as a low-power object may not be familiar to all 

 your readers, especially when the stellate hairs arc 

 viewed with strong condensed light, as from a good 

 lamp intensified by a bull's-eye condenser. The under 

 side has this hair much denser than the upper, and 

 seen there, resembles a rock covered with green 

 seaweed and dotted with glittering silvery sea 

 anemones. A portion of the epidermis mounted as 

 a transparent object polarises well, the hairs polarising 

 while the ground does not. I shall be happy to send 

 a leaf to any one, in stamped addressed envelope. — 

 G. Pirn, Monkstoivn, Dublin. 



Dull Objectiyes. — It would be a good thing if 

 some really authoritative decision could be obtained on 

 the subject, "What is the best substance with which 

 to wipe object-glasses?" There is, at present, such 

 " glorious uncertainty " in connection with the 

 matter, that young microscopists are utterly bewil- 

 dered. In your last issue Mr. W. E. Penny recom- 

 mends an old silk handkerchief as the best for the 

 purpose. Messrs. Beck recommend a clean cambric 

 handkerchief or a piece of soft wash-leather, as most 

 suitable for cleaning the surfaces of eye-pieces, and, I 

 suppose, the surface of the front lens of an object- 

 glass. Dr. Carpenter says, "The best material for 

 wiping glass is a piece of soft wash-leather from 

 which the dust it generally contains has been well 

 beaten out." Mr. Jabez Hogg says : " Keep a piece 

 of well-dusted and very dry chamois leather, slightly 

 impregnated with the finest tripoli or rottenstone 

 powder, in a small box, to wipe your glasses ; a small 

 piece of diied elder-pith is preferred by some for 

 the purpose." It would seem from the above that 

 nothing short of a " Royal Commission" will be able 

 to settle the point. After a careful consideration of 

 Mr. Woolcombe's remarks, it would appear that the 

 cause of the dimness of which he complains, is some- 

 what deeper than Mr. Penny suspects : the real 

 cause being, more probably, cracking of the cement 

 by which the two parts of an achromatic combination 

 are joined ; or, the insinuation of moisture between 

 them giving rise to what is known as " sweating." 

 In either of these cases, the only safe course is to send 

 the object-glass to the maker for repair. — G. J. 

 George, Chorley, Lane. 



Ants killing Snakes. — A friend lately staying 

 in Devonshire, on noticing to a workman the quantity 

 of ant-hills, was told that they did a great deal of 

 good by killing snakes. I should be glad to know if 

 ants do really kill snakes, and if so, how they do it. 

 — Y. V. S. 



