Jan. 1, 1867.] 



HAEDWICKE'S SCIENCE GOSSIP. 



21 



Mounting in Balsam. — I am convinced by my 

 own experience that any-one who wishes to attain 

 proficiency in preparing microscopic objects, must 

 rely upon himself, and not upon directions in books. 

 The latter are often more a hindrance than a help. A 

 " mounting instrument," a " water-bath," a " spirit- 

 lamp," a slider-forceps," an " air-pump," and all 

 the other implements usually recommended, are ex- 

 pensive to obtain, and practically useless when got. 

 For most purposes, a penknife, a camel-hair brush, 

 a pin, and a candle, will be found sufficient. To 

 follow the advice of some writers, it would require 

 a mouth or six weeks to prepare the proboscis of a 

 fly. First it must be steeped in potash ; then it 

 must be washed in water, after which it will take a 

 fortnight to dry. Then it must be steeped in tur- 

 pentine for another week, and dried again before it 

 is mounted. To harden the balsam, the slide has 

 now to be put " in a warm situation," where it may 

 remain from "May till September," and then not 

 be hard. By the plan I adopt the whole of this 

 business may be performed in a few minutes. The 

 length of time the object must remain in the potash 

 will depend upon its texture ; but when it is taken out 

 of the potash, if it is washed with turpentine instead 

 of water, it may be mounted immediately. The tur- 

 pentine most effectually clears it of the " milky ap- 

 pearance," which forms the difficulty of " T. B. N." 

 Having washed the object with turpentine until the 

 milky appearance is gone, place a little balsam upon 

 the glass slip, hold it over the candle until the 

 balsam boils, then place the object in it, and put on 

 the cover. When the slide cools, the balsam will 

 be perfectly hard, and the specimen may at once be 

 cleaned for the cabinet. The whole of this process, 

 from the taking of the object out of the potash to 

 the finish, may be performed in about five minutes. 

 Of course, expertness at the work is gained only by 

 experience; and every preparer will have a way 

 peculiar to himself. The answer to James "W. Impey 

 is : — The hardening of the balsam depends -upon the 

 amount of heat applied to it, and this must be regulated 

 by the state of the balsam and the nature of the object. 

 And if " T. B. N." will wash with turpentine instead 

 of water, the " milky appearance " will cease to 

 trouble him. — T. Craggs, Gatesliead. 



Cement for Slides. — I see amongst several 

 correspondents, J. W. Impey complains of the time 

 balsam takes to harden ; and so it will ; and even 

 after it seems hard, a very slight degree of warmth 

 will soften it. I venture again to mention the way 

 in which I set a great majority of objects. I put 

 them on the slide very slightly damp, put some 

 balsam over them, and the glass at top ; and gently 

 heat them till the water boils away : the balsam 

 takes its place. The vapour of the water takes 

 most of the air away, and a little manipulating with 

 the thin glass removes the rest. This done, the 

 balsam sets hard at once, and three or four minutes 

 will finish the slide. 



I see some of your correspondents find difficulty 

 in dissolving india-rubber, and it is a troublesome 

 thing to do unless they get the right kind of naphtha. 

 If they use india-rubber which has been dissolved, 

 they will find it easier ; but it is best to buy it. 

 Some years ago I wanted some cement to put round 

 slides in which glycerine was used, and, for want of 

 something better at the time, I used the contents of 

 a bottle of preserving waterproof varnish for shoes ; 

 I found it do veiw nicely, and have used nothing else 

 since. It dries quickly and tough, and doesn't peel 

 off the glass. I cannot tell the name of the maker, 



but it came from 39, Queen-street, Lincoln's-Inn' 

 Perhaps the notice of this may prove useful. — 

 K T. Scott. 



_ Tenacity of Life in a Flea. — A few days 

 since one of these irritating little creatures attacked 

 a member of the genus Homo, and while in the act 

 of piercing the skin, the individual placed his linger 

 on it, and put it into a basin full of clean water. 

 This was about eleven o'clock p. m. Next morning 

 it was found at the bottom of the water, to all ap- 

 pearance quite dead. It was then put into an 

 envelope, and placed in the_ gentleman's waistcoat 

 pocket for inspection at his leisure. An hour or 

 two afterwards the envelope was examined, when out 

 jumped the animal with all the agility for which the 

 genus Pulex are remarkable, after having been 

 under water ten hours. Not being an amphibious 

 animal, I cannot understand upon i-.what principle it 

 could escape drowning; having spiracles and a tra- 

 cheal system it would appear impossible that these 

 should not fill with water, and thus kill the little 

 creature ; but it was not so ; it still lives. — /. J. Fox. 



Mounting in Balsam. — The difficulty experi- 

 enced in mounting with Canada balsam may arise 

 in several ways ; the most probable is, that the balsam 

 employed is genuine that is to say, in its thick state ; 

 as imported, such a specimen will not acquire solidity 

 so rapidly as is absolutely necessary for the purpose. 

 Another cause of indifferent mount may be that the 

 vendor has diluted the pure article with commercial 

 spirits of turpentine ; and although this is to a cer- 

 tainty preferable to the undiluted balsam it is by no 

 means satisfactory. If your inquirer will attenuate 

 the pure balsam with camphor (a highly rectifying 

 spirit of turpentine, until it acquires a consistence a 

 little less limpid than olive-oil, he will be, as I have 

 been, perfectly satisfied with the result. I pre- 

 sume its superiority is due to the increased solu- 

 bility which it acquires by the addition of the 

 camphor. I ought to observe that, having mixed 

 as above, the compound should not be used until 

 perfectly clear (it will become so after a few hours). 

 — W. B. 



Blue Birds of Galilee. — I see that a corre- 

 spondent in a late number inquired what was " the 

 blue bird of Galilee." I suppose that fancy may be 

 allowed some scope in the question, but as a matter 

 of fact there are but two birds to which it can be 

 applied — the blue Thrush (Petrocincla cyanea) which 

 is scattered about the Galilean hills and glens in 

 small numbers all the year round, and the Boiler 

 (Coracias garrula) which is very common over the 

 whole country in summer only. The Sun-bird 

 (Nectarinia osea) is quite out of the question. It is 

 not blue, and it barely exists in Galilee • one or two 

 pairs merely straggling into the neighbourhood oi 

 the Lake of Galilee. It is a bird of the Lower Jordan 

 valley and Dead-Sea basin strictly, and even there 

 will only be seen by those who look closely for it. — 

 II. B. Tristram. 



[" T. G. P." writes to us again in support of his 

 opinion that the bird alluded to by Benan, as "so 

 small and light that it can rest on a blade of grass 

 without bending it," must be some such small crea- 

 ture as Cinnyris osea .] 



Bidmusk (Science Gossip, vol. ii. p. 214), called 

 in Persia and the gardens of Northern India, Bed- 

 mooskh (" Boyle Illustrations," p. 345), is Salix 

 Mgyptiaca. — H. G. ^ 



