408 Mr. A. Smith on the Causes of the Loss of the [Apr. 29, 



I. " On a certain Excretion of Carbonic Acid by Living Plants." 



By J. Broughton, B.Sc, F.C.S., Chemist to the Cinchona 

 Plantations of the Madras Government. Communicated by J. 



D. Hooker, M.D., F.R.S. Received March 31, 1869. 



[Abstract.] 



"While the author was engaged in some experimental determinations of 

 the changes that take place in the composition of the Cinchona barks 

 after being taken from the tree, he noticed a somewhat singular circum- 

 stance, which induced him to institute a series of experiments, by which 

 he discovered that the various parts of living plants excrete carbonic acid, 

 not only in their normal condition, but after they have been deprived for 

 days together of all access of oxygen. The experiments were mostly made 

 on cut portions of the plants ; but experiments were also made, for control, 

 on plants as they actually grow. The deprivation of oxygen was effected 

 sometimes by Sprengel's air-pump, sometimes by substituting for air an 

 atmosphere of hydrogen or nitrogen ; while comparative experiments 

 were made on plants supplied with air that had been freed from carbonic 

 acid. The main conclusions to which he was led are those enunciated 

 by the author : — 



1st. That nearly all parts of growing plants evolve carbonic acid in 

 considerable quantities, quite independently of direct oxidation. 



2nd. That this evolution is connected with the life of the plant. 



3rd. That it is due to two causes, namely, to previous oxidation, result- 

 ing after a lapse of time in the production of carbonic acid, and to the 

 separation of carbonic acid from the proximate principles of the plant 

 while undergoing the chemical changes incident to plant-growth. 



II. "On the Causes of the Loss of the Iron-built Sailing-ship 

 ' Glenorchy.-' " By Archibald Smith, Esq., M.A., LL.D., 



E. R.S. Received April 15, 1869. 



When the loss of an iron-built vessel has been caused by an error in the 

 direction of her course by dead reckoning, as derived from her course by 

 compass, it is a question of scientific interest whether the error has or has 

 not arisen from an error in the assumed deviation of the compass. By 

 careful consideration of all the circumstances of the case, and by piecing 

 together the generally scanty fragments of information which can be 

 obtained as to the magnetic state of the ship, a probable or certain answer 

 to this question may be given more frequently than might be supposed 

 possible by those who do not know how perfectly definite and well ascer- 

 tained the laws of the deviation of the compass are, how small is the 

 number of quantities involved which are peculiar to each particular ship, 

 and from what apparently slight indications an approximate estimate of 

 the numerical values of these quantities can be made. 



