60 grammes of carbonate of potash, 

 10 „ arsenious acid, 



326 RECORD OP CURRENT RESEARCHES RELATING TO 



and pliability ; to exclude decomposition for years ; to maintain the 

 consistence of the various parts ; and to give the same results with the 

 lower animals and with all sorts of vegetable substances. Morbid 

 formations removed by an operation will appear after months as if 

 in a fresh state. The Prussian Minister of Instruction has recently 

 officially published the formula for the benefit of the scientific world. 

 The liquid is prepared by dissolving 



100 grammes of alum, 

 25 „ common salt, 



12 „ salti^etre, 



in 3000 grammes of boiling water, allowing the solution to cool, and 

 filtering : to 10 litres of this liquid are added 4 litres glycerine, and 

 1 litre methylic alcohol. 



The guiding principle for its use is that of impregnating and 

 saturating the bodies with the liquid. Substances intended to be kept 

 hereafter in a dry state are soaked in it from six to twelve days, accord- 

 ing \o size, and dried in the air. Hollow organs, as lungs, are filled 

 with the liquid previous to immersion in it, then emptied and dried : 

 intestines should be inflated after emptying. Small specimens, such 

 as crabs, beetles, frogs, &c., if the natural colours are to be preserved 

 unchanged, are not to be driedj but put immediately into the liquid. 



Microphotographical Notes.* — According to Dr. Carl Seller's 

 experience, there is no advantage in objectives specially constructed 

 for photography over other good objectives, provided monochromatic 

 light is used, which brings the visual and the chemical focus in the 

 same plane. 



Having found some difficulty in making a cell to contain the solu- 

 tion of ammonio-sulphate of copper, through which the sun's rays are 

 passed before they enter the substage condenser (the copper salt 

 dissolving almost any cement, and if exposed to the action of the air 

 very rapidly becoming decomposed and turbid), the author uses a cell 

 made of a brass ring lined on the inner side with lead, and having a 

 thread cut on its outside, to which flanged rings are screwed. Upon 

 the edges of the inner ring a ring of rubber packing is "applied, and 

 upon it a disk of plate glass is laid, which is tightly pressed upon the 

 rubber by the flanged ring. Thus a cell is obtained very similar to 

 the round, flat spirit level, and which will hold the ammonio-sulphate 

 solution for months without change. In filling the cell, care should 

 be taken to leave room for a small air bubble, for if the cell is 

 completely filled, the heat of the sun's rays will expand the solution 

 sufficiently to cause leakage. 



At the present time, when dry-plate photography has been deve- 

 loped to such an extent that it has superseded in a great measure the 

 old wet process, it has been thought that it would be the most simple, 

 economical, and satisfactory process for photomicroscopy ; but after 

 repeated trials by Dr. Seiler, as well as by others working in the 

 same direction, it is found that it is not only more expensive, but also 

 takes more time in the long run. The reason of this is, that it is 



* ' Am. Jouru. Micr.,' iv. (1S79) p. 15i). 



