1892.] MICROSCOPICAL JOURNAL. 123 



thick liquid ; pour oft' the soapy water, and continue the washing 

 until the water is absolutely clean. 



Examine a minute quantity of the material with the micro- 

 scope ; if the shells are not clean and bright begin again with the 

 nitric acid and bichromate and follow with the soap as before. 

 Use a four-inch test tube and a lamp of any kind. When boiling 

 have about half a teaspoonful of fluid in the tube; when washing 

 fill the tube with clean water. Revolve tlie test tube sharply be- 

 tween the fingers at times during the process of settling, to de- 

 tach diatoms adhering to the sides of the glass tube. Do not 

 hurry the boiling or the settling processes. Pour oft' the wash' 

 water very slowly so as not to disturb the deposit in the bottom oi 

 the test tube. Keep the cleaned diatoms in a small vial of clean 

 water. 



To Mount Diatoms "Dry." — All ''dry" mounts of dia- 

 toms, whether " strewed " or '' selected," are liable to destruction 

 or deterioration from an accumulation of moisture upon the under 

 side of the cover, which moisture, sooner or later, and in defiance 

 of all precautions, always makes its appearance. " Dry mounts" 

 are. therefore, always more or less unsatisfactory and unreliable 

 and to be avoided as much as possible. The best method of 

 mounting diatoms " dry" — whether for " test" or as " arranged " 

 slides — is to make a cell of the best asphalt, of the necessary thick- 

 ness by adding coat upon coat of the asphalt, not by making the 

 cell of suflicient depth at one operation. Spread the diatoms upon 

 the cover; if necessary " burn" them upon the cover, i. e.^ place 

 the cover upon a piece of thick platinum foil and raise it, slowly 

 and carefully, to a dull red heat over the flame of a ^ Bunsen" 

 burner ; thoroughly heat the slip with the asphalt cell upon it ; 

 whilst it is hot (and therefore certamly free from all damp or 

 moisture) place the equally hot cover cai'efully upon the cell, 

 pressing down the cover and making sure that it adheres thor- 

 oughly and evenly to the cell ; run a ring of asphalt round the 

 edge of the cover ; when this is hard, ring the cell with two coats 

 of white zinc cement, letting the first coat dry thoroughly before 

 applying the second. — Cole. 



Hudson River "Fiord." — Dr. Arthur M. Edwards has 

 been for some time investigating the deposit thrown down dur- 

 ing the Champlain period in the Hudson river, New York, more 

 especially to find out if it is the same as that of the bay of Newark, 

 N. J., and has decided that they are different, that of Newark 

 being newer than that of the Hudson river. He has examined 

 the soundings from the Hudson river " Fiord" made by Mr. A. 

 Lindenkohl, of the U. S. Coast Survey. 



A list of the forms identified may be found in The American 

 Journal of Science., vol. xliii, March, 1S92. 



The microscopic organisms are not those of the Newark bay, as 

 they are not of brackish or fresh-water origin as those are, show- 

 ing the " Fiord " is not a continuation of Newark bay but rather 

 of the Hudson river. 



