OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 647 



preserved separately subsequent examination did reveal slight differences. The results 

 obtained by Dr Philippi (1) of the German Antarctic Expedition show, however, that 

 considerable differences may exist between the surface layers and deeper portions of 

 the deposit in certain areas and indicate the importance of dividing the plug of 

 deposit into two or more portions for separate examination, and also perhaps of using 

 longer mud tubes on the sounder. Dr Philippi recommends tubes 1 metre long. 

 Tubes longer than this have the disadvantage that they may stick so firmly that when 

 reeling in is commenced the wire is very apt to snap. 



Material was also obtained in a number of instances from the trawl. When this was 

 small in amount it had, of course, to be taken simply as it was, possibly partly washed 

 on the way up and not truly representative of the bottom material in situ ; but where 

 abundant, and if a sample were desired in bulk, the outer portions were discarded and 

 a portion taken from the interior of the mass of mud in the trawl, as this could be 

 regarded as truly typical of the deposit. The whole of the remainder of the material 

 was then emptied into a large zinc cylinder built up of a series of rings, at the bottom 

 of each ring being a sieve of wire mesh, the sizes of the mesh in the various rings being 

 1^ inches, | inch, ^ inch, and ^ inch respectively. In this cylinder the material was well 

 washed with a stream of water from a hose, all clayey matter and particles under ^-^ inch 

 diameter washed away, and the rock fragments, pebbles, gravel, sand, etc., sorted out 

 according to their size by the different sieves. The material from each of these was 

 preserved separately for further examination. 



Whenever a specimen of deep-sea deposit was procured, notes were made at the time 

 of the mode whereby it was obtained and of its amount, colour, consistency, and 

 general physical characters. A rough examination was frequently made on board at the 

 time of obtaining it, but in nearly every instance the detailed examination was made on 

 the return home of the Expedition. 



This detailed examination was made after the plan devised by Sir John Murray 

 and Professor Renard, and described by them in the volume of the Challenger reports 

 dealing with deep-sea deposits (2). This plan could, of course, only be carried out in 

 its entirety where a sufficient amount of the sample was available. There was amply 

 sufficient in the majority of cases ; but where there was not, the quantitative determina- 

 tion, for instance, of calcium carbonate, had to be omitted and only an estimation given 

 of the relatiA^'e amounts of calcareous organisms and of the other constituent elements 

 of the sample. For a full description of the method the Challenger volume on deep- 

 sea deposits may be consulted : the following is a brief description of the routine 

 I followed. 



The macroscopic characters, both in the wet and dry condition, were first noted. 

 Then the percentage of calcium carbonate in a dried weighed sample was ascertained 

 by analysis. The residue obtained after removal of the carbonate of lime was then 

 well rubbed, stirred, and shaken with abundance of water, and submitted to a process 

 of fractional decantation. The first decantations carry off that part of the residue 



