Are we, therefore, to conclude that he has blundered in his analysis, or that Lehmann has done so? On carefully comparing the two sets of investigations, I conclude that there is no necessary contradiction _in the facts_: that both may be, and in all probability are, quite correct as regards their chemical results; but that Dr. Smith has only attacked half the problem, while Lehmann has grasped the whole. All the popular stimulants, refreshing drugs, and ‘pick-me-ups’ have two distinct and opposite actions—an immediate exaltation which lasts for a certain period, varying with the drug and the constitution of its victim, and a subsequent depression proportionate to the primary exaltation, but, as I believe, always exceeding it either in duration or intensity, or both, thus giving as a nett or mean result a loss of vitality. Dr. Smith’s experiments only measured the carbonic acid exhaled from the lungs _during the first stage_, the period of exaltation. His experiments were extended to 50 minutes, 71 minutes, 65 minutes, and in one case to 1 hour and 50 minutes. It is worthy of note that, in Experiment 1, 100 grains of black tea were given to two persons, and the duration of the experiment was 50 and 71 minutes; the average increase was 71 and 68 cubic inches per minute, while in No. 6, with the same dose and the carbonic acid collected during 1 hour and 50 minutes, the average increase per minute was only 47·5 cubic inches. These indicate a decline of the exaltation, and the curves on his diagrams show the same. His coffee results were similar. We all know that the ‘refreshing’ action of tea often extends over a considerable period. My own experiments on myself show that it continues about three or four hours, and that of beer or wine less than one hour (moderate doses in each case). I have tested this by walking measured distances after taking the stimulant and comparing with my walking powers when taking no other beverage than cold water. The duration of the tea stimulation has been also measured (painfully so) by the duration of sleeplessness when female seduction has led me to drink tea late in the evening. The duration of coffee is about one-third less than tea. Lehmann’s experiments extending over weeks (days instead of minutes), measured the whole effect of the alkaloid and oil of the coffee during both the periods of exaltation and depression, and, therefore, supplied a mean or total result which accords with ordinary everyday experience. It is well known that the pot of tea of the poor needlewoman subdues the natural craving for food; the habitual smoker claims the same merit for his pipe, and the chewer for his quid. Wonderful stories are told of the long abstinence of the drinkers of maté, chewers of betel-nut, Siberian fungus, coca-leaf, and pepper-wort, and the smokers and eaters of haschisch, &c. Not only is the sense of hunger allayed, but less food is demanded for sustaining life.