of the Fishery Board for Scotland. 



Collectio7i of the Samples of Water. 



The samples were collected by means of the slip water-bottle devised 

 by Mr J. Y. Buchanan. The construction and working of this water- 

 bottle, which is made of brass, will be readily understood by reference to 

 figs. 1 and 2 Plate VI. 



The body A consists of two discs a and a', separated by three radi- 

 ating brass plates cc. About quarter of an inch of the upper outer edge 

 of the disc a is cut away, and its place taken up by a ring of india- 

 rubber, indicated by the shaded line g. On its lower surface the disc <x, 

 which is perforated in the centre, carries a stopcock h' being a small 

 plug attached to the bottle by a short piece of chain, to prevent any mud 

 from lodging in the stopcock, should the water-bottle accidentally touch 

 the bottom. The disc a' carries on its upper surface a hollow dome d. 



The other part of the apparatus consists of the hollow cylinder B, 

 which is first strung on to the line, to which the body A is then attached 

 by means of a ring. Holding the cylinder B in the hand, the body A, 

 with a heavy weight attached, is let down to the desired depth. When 

 this has been reached the cylinder B is allowed to run down the line, its 

 lower edge ultimately coming to rest on the india-rubber ring g. During 

 the descent of the cylinder B, free circulation of the water takes place 

 through the ring of holes near its upper extremity. The water contained 

 by the cylinder B, at the moment of its reaching A, is expelled upwards 

 by the dome d, which finally closes the holes, and thus prevents the 

 escape of water while hauling up. After removing the plug h\ the water 

 thus collected can be run out through the stopcock. 



The working of this ingenious though simple contrivance is thus a very 

 easy matter. With proper care, and by rejecting the sample whenever any 

 displacement of the rubber or hollow cylinder is noticed, very reliable 

 results may be obtained. 



The samples collected were in most cases bottom samples; that is, samples 

 collected at about one fathom above the true bottom. The surface samples 

 were collected at about one fathom below the true surface. 



Preservation of the Samples. 



I at first intended to determine the specific gravities of the samples 

 within a few days of their collection, and for this purpose brought a balance 

 with me to the little station-house of the Expedition. 



Practical difficulties, however, which I need not detail, stood in the 

 way of the attainment of the necessary conditions for accurate weighing, 

 and I therefore, after several unsuccessful attempts, reluctantly gave up 

 this part of my original plan. 



I had taken with me a not very large stock of glass stoppered bottles of 

 about 750 cc. capacity, but when I saw that the samples would have to be 

 kept a considerable time before being examined, I discarded the glass 

 stoppers, and adopted the following method in order to prevent loss by eva- 

 poration. The carefully cleaned bottle was rinsed out several times with 

 small quantities of the sample of water, run out direct from the slip water- 

 bottle, and then filled up nearly full. A carefully selected ordinary cork, 

 well moistened with some of the sample, and covered with a piece of pure 

 thin sheet rubber similarly moistened, was then inserted well into the neck 

 of the bottle. The cork and rubber were then cut flush off with a sharp 

 knife, and the entire mouth of the bottle covered with a quantity of fine 

 sealing-wax. This method, which is recommended by Bunsen for the pre- 



