472 Mr. J. Murray on Oceanic Deposits examined 



bottom in each sounding. Sometimes the tube has been forced fully 

 18 inches into the bottom, and has brought up frequently as much as a 

 quart of the ooze, mud, or clay. When the tube arrives on board the 

 contents are carefully removed, and the colour, extent, and arrangement 

 of the section* is noted. A portion is washed several times in distilled 

 water and dried, a portion is submitted to a rough analysis, and the 

 remainder, if any, is preserved in spirit. 



The analysis consists in determining so far as possible : — 



1. The kinds of organisms present, and their relative abundance, 

 whether carbonate of lime or siliceous, and whether alive or dead. 



2. The kind and quantity of amorphous and mineral matter, and its 

 ratio to the remains of the above organisms. 



This is accomplished by decanting the finer from the coarser particles, 

 and examining each with the microscope. When carbonate of lime is 

 present this is removed by weak acid, and the specimen is again examined. 

 When manganese is present in great quantity this is removed by strong 

 hydrochloric acid, and again an examination is made. Very frequently 

 portions of the upper layers are placed in colouring solutions (as carmine, 

 magenta, &c), for the purpose of rendering more distinct any organized 

 material, should any be present. 



When the dredge or trawl brings up mud, a considerable quantity is 

 preserved for future work, and what remains is carefully sifted. The 

 siftings are examined and preserved. 



Lately it has been the custom to send down tow-nets loosely attached 

 to the trawl or dredge and at the weights in front of the trawl. These 

 often bring up specimens of the bottom when the trawl fails to do so. 

 As these nets do not probably sink deep into the ooze, they give us a 

 surer idea of the nature of the surface-layers than previously obtained by 

 the trawl alone. 



List of the Soundings and Dredgings, with an abstract of the nature of the 

 bottom in each case where a sample has been procured. 



Explanatory Note. — The following remarks under each sounding or 

 dredging have been abstracted from notes made daily during the cruise. 

 In making the abstract the object in view has been to indicate so far as 

 possible the relative abundance in each sample of — 



Eemains of carbonate-of-lime organisms ; 



[Remains of siliceous organisms ; 



Mineral particles, as quartz and mica ; 



Glauconite, pumice, manganese, &c. ; and 



Amorphous clayey and calcareous matter. 

 It has been thought that, however incomplete, such an abstract will in 

 the mean time be useful to naturalists and geologists. It will give some 



* i. e. the vertical section, which is always greater the further the tube has been 

 forced into the ooze or clay. 



