so REPORT — 1841. 



existed in the quantity of carbonic acid given off from the system, when 

 under the influence of opium. With this view the quantity eliminated before 

 and after a dose of this drug had been taken, has been repeatedly measured. 

 The experiments were performed by breathing through a solution of pure 

 potassa, and by Aveighing the result, as well as extricating the carbonic acid 

 acquired. It is unnecessary to enumerate the modifications in the apparatus 

 used, in order completely to separate the watery vapour, to prevent the 

 chloride of calcium employed for this purpose from descending into the 

 potassa and negativing the result, to obviate the escape of minute portions 

 of the solution of potassa on passing the expired air through it ; the conclu- 

 sion arrived at is, that much more carbonic acid is given oif simultaneously 

 with the production of the effects of opium. Not only is the number of re- 

 spirations increased, and thus more is eliminated, but in an equal number of 

 respirations there was found to be an increase of at least one-tenth. The 

 quantity of opium. taken was equivalent to a grain and a half of the extract, 

 and the observation was made as soon as the effects (tightness of the fore- 

 head, slight sensation of nausea, accelerated pulse, quickened breathing, and 

 general feehng of tranquillity) were perceived. It were easy to show the gene- 

 ral likeness of the action of narcotics to those produced by carbonic acid gas ; 

 but to connect them with this last-named agent will require further inquiry. 



Allow me now, in conclusion, to state that the ideas expressed in this paper, 

 are submitted with great deference to the Meeting ; that they are advanced 

 with the view of calling attention to certain interesting but obscure pheno- 

 mena, and are forwarded in compliance with the desire of the Association. 



15 Welbeck Street, July 1841. 



Report on Discussions of Bristol Tides, performed by Mr. Bunt 

 under the direction of the Rev. W. Whewell, F.R.S. 



[With Plates 2, 3, 4, 5.] 



The careful and intelligent manner in v/hich Mr. Bunt had conducted those 

 Discussions of the Tides, on which the grants of the British Association in 

 former years had enabled me to employ him, made me very desirous of continu- 

 ing to profit by his labours, in order to bring, if possible, the ascertained laws 

 of the tides nearer to the observations. With this view I applied at the last 

 meeting for an additional grant of 50^. ; and have now to report the pro- 

 gress which has been consequently made in our tide discussions. We began 

 by considering the possibility of improving the correction for lunar declina- 

 tion, and the determination of the anterior epoch of the semimenstrual in- 

 equality. But it did not appear very probable that any additional discus- 

 sion of the observations which we had before us would give us any additional 

 accuracy, commensurate with the great labour which must be undergone in 

 making the trial. I was therefore the more ready to follow out a suggestion 

 of Mr. Bunt's, who wrote to me in January last that he had recently deter- 

 mined to try whether he could perceive any effect on the heights of high 

 water at Bristol produced by atmospheric pressure. He adds, " I accord- 

 ingly arranged the errors of the calculated heights for 1840 in columns for 

 every two-tenths of an inch of the barometer, observed contemporaneously 

 with the tide." 



From a diagram given in his letter, the average effect appeared to be about 

 15 inches depression of high water to 1 inch rise of mercury in barometer. The 

 consistency of these results leaves no doubt as to the fact of a sensible effect on 

 the heights from this cause. In his letter, he adds, " Some subsequent trials 



