250 THE AMERICAlSr MONTHLY [July 



the flame of burning- camphor until the surface is evenly 

 coated. 



I found it tedious to rule each line separately, so I hit on 

 a plan which has proved very successful. I took a paper 

 of pins, and after selecting- an even row I g-ummed it to a 

 g-lass slip, and fixed a handle to the other side of the slip. 

 By this means I could rule all the parallel lines at one 

 stroke, and by another stroke all the lines at rig-ht ang-les 

 to these, thus dividing- the slide into equal spaces. 



The spaces can then be numbered with a mounted 

 needle. A weak solution of shellac in spirit should then be 

 poured over the blackened surface and allowed to dry, 

 when it will be found quite fast. The specimens may then 

 be stuck on in the ordinary way with g-um. 



The g-um I use is a mixture of equal parts of g-um arable 

 and trag-acanth dissolved in cold water with a little g-lycer- 

 ine, and the whole evaporated in a small ointment-pot and 

 kept dry. A drop of water placed on the surface of the 

 g-um will dissolve enoug-h for a slide in a few seconds. 

 This combination neither breaks the specimens nor lets 

 them g-et loose. — Postal Journal. 



Batrachospermum. To Mount. — I have found no diffi- 

 culty in perserving- Batrachospermum in g-lycerine by 

 Hautzsch's method. Hautzsch's fluid consists of a mix- 

 ture of alcohol, 3 parts ; distilled water, 2 parts; and g-ly- 

 cerine, 1 part. This is nearly of the same specific g-ravity 

 as water. The specimen is floated in a cell filled with 

 this fluid, and set by, lig-htly covered to keep out dust. 

 The spirit and water g-radually evaporate and leave the 

 g-lycerine behind. In this way the water in the texture of 

 the plant is g-radually replaced by g-lycerine, and we avoid 

 that shrinking- from exosmosis which takes place when the 

 specimen is suddenly transferred from water to a dense 

 fluid like g-lycerine. — Postal Journal. 



Oxalic Acid For Preserving The Color of Dried 

 Plants. — The importance of a well-selected herbarium is 

 known to every botanist of the present day. It presents 

 to him the most important specimens of the flora so far as 



