HYDROGRAPHY. , x 



parts of it are the boiling-flask A and the analysis-burettes B. The method used for the analysis 

 was in short as follows: The air is expelled from the boiling-flask A by means of mercury, and it is 

 filled with a certain volume of sea-water, which is boiled out The gas extracted by this process, is 

 driven into the burette B,, where it is measured over water, and from there it is led into the burette 

 B 2 , where the carbonic acid is absorbed; finally the remaining gases are transferred to B $ , where the 

 oxygen is absorbed. When this boiling out has taken place, a quantity of sulphuric acid is added to 

 the water in the boiling-flask, and the gases remaining in the water are by repeated boilings extracted 

 from it, and likewise transferred to the burettes, where they are measured. 



A is a cylindrical glass-reservoir of 200 to 250° c,n capacity, formed into the shape of a tube at 

 the top and at the bottom. The lowermost of the tubes has a diameter of 6 mm , and at a is a mark 

 that is etched on it, below which a cock is fitted. It carries a bent down service-pipe with the cock 

 H 5 , and this pipe is again by means of an India-rubber tube connected with a glass tube G 20 cm long 

 and 4 mm wide. On the upper tube, the diameter of which is io mm , is likewise etched a mark at b. 

 The space between the two marks, the service-pipe not included, is fixed once for all by weighing off 

 the quantity of distilled water that can be held between them. The lowermost tube is by a strong 

 India-rubber tube through the cock H^ in communication with a large mercury-reservoir, the contents 

 of mercury of which shall be sufficient to fill the boiling-flask A as well as the condenser C. The 

 mercury-reservoir is a cylindrical wooden coop covered with a lid of wood, and the lower part of it 

 is lengthened downwards into the shape of a narrow tube, to which the India-rubber tube from the 

 boiling-flask may be attached. The boiling-flask A is warmed in an air-bath to prevent it from being 

 heated too suddenly. It is surrounded by a brass tube, the bottom and lid of which likewise are 

 made of brass. In the middle of the lid is an orifice, through which the upper glass tube from A 

 proceeds packed with asbestos. The bottom plate is screwed on to the brass cylinder, and like the 

 lid it is separated from the boiling-flask A by a plate of asbestos. In the middle of the bottom, a 

 hole is pierced, in which a small brass tube — encircling the lower glass tube which proceeds from 

 A, and separated from this tube by asbestos — is soldered on by silver. This brass tube which goes 

 down nearly to the service-pipe, as well as the bottom-plate, are cut longitudinally into two parts of 

 equal size. As the two halves of the brass tube are to be kept closely together round the asbestos- 

 packing, a larger and thinner brass tube, cut open at the one side to enable it to be led past the 

 service- pipe, is fitted round the first mentioned brass tube. At the foot it is supplied with a collar 

 of brass, by which the boiling-flask and its jacket are attached to a wooden stand. 



The condenser C, of a capacity of 80 cubic centimetres, is at its upper and lower end contracted 

 into the shape of a tube. The lower tube is similar in dimensions to the upper tube that proceeds 

 from A, and it communicates with this tube by a short rubber tube, in which the two tubes nearly 

 meet. The upper tube has only a diameter of 2 mm , and it is supplied with the threeway cock JJ, 

 which, like // 5 , must be ground with the greatest accuracy. The upper tube of the threeway cock is 

 at the top enlarged into the shape of a funnel T, the sidetube K communicates with the burette B x . 

 The glass reservoir C is enclosed in a water-bath consisting of a short wide glass tube, the bottom-ends 

 of which are faced by grinding and closed with India-rubber sheets, through which the two tubes of 

 the receiver pass, which is likewise the case with an induction pipe at the bottom and an eduction 



