1865.] On the Adds of the Lactic Series. 191 



to be attributed partly to the want of the transverse armour-plating at the 

 extremities, and to the comparatively small number of bulkheads giving a 

 smaller e than in the iron-plated ships of the Royal Navy, and partly to 

 the armour-plating of the sides being continued on each side of the com- 

 pass giving a large a, and in this respect resembling the effect of the 

 armour-plating in the Royal Oak class of ships in the Royal Navy. 



22. The large amount of the heeling error in the Main-deck Compass 

 and its direction is remarkable. 



23. The Pervenetz' sailed for the Baltic on the 8th of August, 1863. 



24. The only change in her magnetism on the voyage was an increase 

 in the -f (, which was no doubt owing to the starboard side being south. 



25. The principal practical conclusions to be derived from the observa- 

 tions in the ' Pervenetz ' seem to be, 



(1) That iron ships should be built head south. 



(2) That in whatever direction an iron armour-plated ship is built, 

 she ought to be placed in the opposite direction while plating, so as to 

 reduce the semicircular deviation as much as possible. This results also 

 from the observations made in the ships of the Royal Navy ; but the plan 

 of plating a ship in the opposite direction to that of building was first 

 practised intentionally, and with the design of reducing the semicircular 

 deviation, in the 'Pervenetz,' and, as will have been seen, with complete 

 success. 



(3) That great and rapid changes take place in the semicircular de- 

 viation some time after launching. 



(4) The great amount of information both as to the semicircular de- 

 viation and the heeling error, which can be obtained by appropriate 

 observations made while the vessel is building. 



(5) The importance for this and other purposes, of reducing and 

 recording the deviations of all iron ships, so as to obtain the values of the 

 coefficients, and particularly X and 25, and to be able to estimate them in 

 any new ship of the same class. 



(6) The great importance of preparing a proper place for the reception 

 of the Standard Compass in the construction of an iron ship. 



III. " Notes of Researches on the Acids of the Lactic Series. No. V. 

 Action of Zinc upon a mixture of Ethyl Oxalate and Amyl Io- 

 dide." By EDWARD FRANKLAND, F.R.S., and B. F. DUPPA, 

 Esq. Received March 30. 



When a mixture of equivalent proportions of ethyl oxalate and amyl 

 iodide is digested with granulated zinc at 70 C., the zinc is gradually 

 dissolved, while much hydride of amyl and amylene are given off. The 

 mixture finally assumes a viscous or semisolid condition, and, when treated 

 with water, produces a further quantity of hydride of amyl, which distils 



