TRANSACTIONS OP THE SECTIONS. 41 



sure ; the capacity of this vessel being -j^ths of a cubic inch, gives a pressure equal to 

 275 atmospheres. 



In the second experiment an explosion took place when 179 cubic inches had been 

 evolved by the voltameter; the concussion was so loud that a friend who was in the 

 laboratory likened it to the report of a company of soldiers firing with blank cartridge. 

 The leather (placed between two portions of the apparatus to ensure insulation) was 

 forced out with such strength as to pass through the hat of my assistant, who was about 

 4 feet from the apparatus. 



In this instance, presuming that the whole quantity of gases as evolved in volta- 

 meter had also been evolved in apparatus, we obtain the enormous pressure of 447§ 

 atmospheres. 



In one experiment we have an undoubted pressure of 275, and in the other a cal- 

 culated pressure of 447 atmospheres, at which water is electrolysed and conducts with- 

 out apparently offering any extra resistance to the current, for during the whole of 

 these experiments the needle of the galvanometer remained steadily deflected. 



On the Corrosion of Iron-built Ships by Sugar Cargoes. 

 By John Hall Gladstone, Ph.D., F.R.S. 



The author stated that his attention had been drawn by his brother, Mr. George 

 Gladstone, to the fact that the owners of iron-built vessels object to sugar cargoes, on 

 account of the rusting of the metal by the saccharine juices that exude from the casks; 

 and this had led to a chemical examination of the reaction then instituted. It was 

 found that when pieces of iron were placed in bottles containing a solution of cane- 

 sugar, the metal at the edge of the liquid soon became deeply corroded, but that 

 which was permanently immersed in the fluid remained bright for a considerable 

 time. The solution soon gave indications of the presence of protoxide of iron, which 

 absorbing oxygen from the atmosphere was speedily thrown down as the red sesqui- 

 oxide, leaving the sugar free to dissolve a fresh quantity of iron, the precipitated 

 oxide in the mean time forming a deposit. After eighteen months, the liquid was of 

 a deep red-brown colour; it became pale blue with ferrocyanide of potassium, black 

 ■with sulphuret of ammonium ; alkalies produced no precipitate ; nitric acid peroxi- 

 dized it. A portion dried and analysed gave 2078 parts of metallic oxide to 100 of 

 combined sugar, which is almost exactly in the proportion expressed by the formula 

 Cjj Hji Oji, FeO. The author, however, considered that this might differ from the 

 true composition by an equivalent of water. No such iron compound could be 

 formed by direct combination. In vain was it attempted to dissolve any freshly- 

 precipitated and well-washed oxide of iron in a solution of sugar; and almost equally 

 unsuccessful was the attempt to do so when the oxide was liberated by means of 

 potash in the presence of sugar itself. It was found that under all circumstances of 

 dilution or quality of the sugar solution, iron was attacked ; the presence of zinc in 

 contact with the iron did not prevent its being acted upon ; nor was there any marked 

 difference when the salts of sea-water, or the nitrates, sulphates, or chlorides of the 

 alkalies were added to the solution. No other ordinary metal was found to be so 

 easily acted upon as iron. Copper was very little affected by the sugar. Lead was 

 slowly attacked, indications of the presence of its oxide in solution being obtained 

 after three days' exposure. Tin appeared to give the binoxide. Zinc was little 

 aftected when alone ; it seemed to be dissolved more quickly when in contact with 

 iron. It is doubtful whether mercury was touched by the sugar solution ; silver 

 certainly was not. The author regretted that his experiments did not suggest any 

 method by which the corrosion of iron ships by sugar cargoes might be prevented. 

 They showed rather the strong disposition to combine that there is between the two 

 substances; and how a small quantity of sugar may eat continuously into a large 

 sheet of iron. The attention of chemists was especially drawn to the fact that the 

 iron enters into combination with the organic matter, not when it has already been 

 oxidized, but only when in a metallic condition, rendering the action, as would be 

 imagined, more complicated. 



On the Spontaneous Decomposition of Xyhidine. 

 By J. H. Gladstone, Ph.D., F.R.S. 

 This was a description of the changes that had taken place in a specimen of xyloi^ 



