MICROSCOPIC OBJECTS. 155 



always be placed downwards, or from the microscope, 

 and the other side next the eye or instrument. The 

 softness of mica prevents it being cleaned like glass ; it 

 should therefore be kept as free from dust as possible, 

 and only brushed lightly with a camel's hair pencil when 

 necessary, and never touched by the fingers. When 

 test- objects are to be mounted in this way, only one or 

 two cells should be mounted in each slider, which will 

 lessen their liability to injury. 



(3.) Method of Mounting very minute Transparent 

 Objects in Brass Sliders. — A simple and convenient 

 method of preserving such objects (contrived by Dr. 

 Goring) is between plates of talc within a folded piece 

 of very thin plate-brass, as shown in the annexed figure. 



These shders are so easily formed that any person with a 

 penkife and scissors can make them. Procure a piece of 

 latin brass about the thickness of banlaiote-paper, and 

 cut off a shp the length of the intended slider, and twice 

 its breadth ; then fold it down the middle and make a 

 small hole for the object (see the figure) : now take a 

 piece of talc a little narrower than the brass and make a 

 slit with the penknife down the middle, leaving a portion 

 uncut at each end, so as not to separate it ; then put in 

 your object, and fold it as you did the brass ; lastly, 

 insert the talc thus folded between the sides of the brass, 

 and pinch the edges of the latter close, and the sHder is 



p 2 



