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NOTES AND CORRESPONDENCE. 



Microscopic Hints from Australia. — The EditorS have received 



a copy of the ' Transactions of the Victorian Institute,' in which 

 is a paper on ' Microscopic Investigation,' by Mr. W. S. Gib- 

 bons. From this paper they give an extract, and also add some 

 illustrations, which have been forwarded to Mr. Jabez Hogg 

 by the Author, for the purpose of explaining some of the 

 apparatus he has successfully employed. 



" Some years since I made some experiments in the use of 

 the air-pump in making microscopic preparations, believing that 

 it had not then attracted the attention of operators. Since 

 that time, I found in a recent work an account of some uses 

 that had been made of that insti'ument, but that which I found 

 most advantageous was not mentioned, and appeared to have 

 escaped the experimenter ; while that most dwelt upon in the 

 work in question is one that I abandoned as unavailing, nor 

 have I seen occasion to change the opinion. The operator 

 quoted immerses the objects in balsam, and then places them 

 on a dry hot-bath under the receiver of an air-pump ; the air is 

 supposed to be extracted by this process fi'om the minute pores 

 or cells, and its place supplied by the balsam. I found, however, 

 that in the majority of cases the 



viscidity of the balsam retains 

 the bubbles of air even when 

 they escape from the object, and 

 that many of them return to 

 their original positions on the 

 restoration of atmospheric pres- 

 sure. The plan I recommend 

 as preferable, is to immerse the 

 object in a bath of turpentine, 

 and exhaust it before applying 

 the balsam. The limpidity of 

 the turpentine allows the free 

 escape of air, and when the 

 object is removed from the bath 

 to be mounted, the balsam then 

 blends with the turpentine, and 

 follows it into minute cavities 

 whither it could not alone have 

 penetrated. 



Fig. 2. 

 Steam Bath. 



Conical tin-boiler, 5 inches tliameter, to 

 vaporize a small quantity of water over 

 a lamp. 



B. Cage of perforated metal to hold the 



C. objects C. It fits tightly at the collar 



D. and is stopped by earth with a small 



escape- pipe, so that the steam must 

 pass round the object. 



