ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 531 



The algse are first washed in fresh water directly they are taken from 

 the sea, to get rid of all sea-salts ; they are then floated on to writing- 

 paper, and dried by gentle pressure between sheets of white blotting- 

 paper. When apparently dry, they are put between fresh blotting- 

 paper and packed away in a dry place, where they must be kept 

 perfectly free from the access of light. 



When quite dry, cut off the number of pieces required and soak in 

 old oil of cloves for a sufficient length of time to render them trans- 

 parent, keeping them in the dark during the whole time. When 

 soaked sufficiently, take them out of the oil and lay them upon clean 

 white blotting-paper to absorb the excess, and mount in the ordinary 

 way with cold balsam and benzol, on a cold slide, using a cold cover, 

 and the result will be satisfactory. It is the operation of soaking the 

 algte in turpentine and the mounting in warm balsam that does the 

 mischief, and it should not be forgotten that if the mounted slides are 

 constantly exposed to the light they will bleach in time. 



There are two points which should be noted : old oil of cloves 

 must be used ; the neio is clear and of a very light yellow colour, 

 while the old is more viscid and of a clear light brown. The other 

 point is in the preparation of the balsam, that used in the foregoing 

 preparations is at least thirteen years old, and most, if not all, the 

 turpentine it originally contained has evaporated from it ; it has Ijeen 

 solid for years. The method adopted for bringing it into solution is 

 to pour some benzol into the jar in which it is contained, and when 

 sufficient has dissolved it is poured out into the bottle marked balsam 

 and benzol. By this means only a thin layer of balsam is taken out 

 each time, and having been exposed for a long time to the air it has 

 lost the whole of its turpentine. 



Soap for Preparing and Cleaning Diatoms.* — Professor Hamilton 

 L. Smith writes as follows : — " Many persons who have faithfully tried 

 the processes recommended in the books find, much to their disgust, 

 that after all the trouble and care there will always be a large 

 amount of flocculent matter, which neither acids nor burning will 

 remove, and which will cause the diatoms to clot together and make 

 the completed mount a rather dirty object to behold. Turning from 

 their own preparations to those of Moller, and others who may have 

 the secret, they know that there is somewhere a knowledge they 

 do not possess and which has not yet crept into the books. And this 

 is true. I was not myself aware of the remedy until long after I 

 wrote the article which the editor of this journal copied from the 

 ' Lens ' into his little book entitled ' Diatoms.' 



I have made it known to many, but, so far as I am informed, the 

 process I am about to describe has not been published. I do not 

 know whether ' Moller's secret' has leaked out, and so has reached 

 me in the course of my extensive correspondence, for it is not my own 

 invention, and indeed I cannot now remember just when or where it 

 was first breathed to me, for I have known it for some years, but 

 certainly with no ' injunction to secrecy.' I can assure the disgusted 



* Aracr. Journ. Micr,, v. (1881) pp. 257-8. 



