INDUSTRIAL PROGRESS DURING THE YEAR 1872. X xxi 



ing a loss of caffeine by sublimation is sustained ; but a de- 

 coction made from strongly roasted coffee by percolation 

 contains more caffeine than when made from the slightly 

 roasted bean, since the roasting makes it easier to extract. 

 Prepared as usual, by pouring 6 to 10 times its weight of 

 boiling Avater over ground coffee 3 or 4 times, nearly the 

 whole of the caffeine is extracted. In such a cup of coffee, 

 prepared from 16f grammes of dry coffee,*there is from 0.10 

 to 0.12 gramme of caffeine; the same amount is found in a 

 cup of tea prepared from 5 or 6 grammes Pekoe tea. Caffeine 

 acts directly on the spinal cord, and causes tetanus ; in frogs, 

 injected subcutaneously, in doses of 0.005 gramme ; in rab- 

 bits, injected into the jugular vein, 0.12 gramme ; and for cats 

 and dogs, 0.2 gramme. It quickens the heart's action, and re- 

 duces the pressure of the blood. Zuntz shows that carbonic 

 oxide, when in the blood, is not separated all at once, but is 

 evolved at intervals. He believes, therefore, that in poisoning 

 by this gas, artificial respiration should be kept up for a long 

 time, in hope of resuscitating the victim. Komensky has ob- 

 served that trichlorhydrin is an anaesthetic when taken by the 

 stomach. Owing to its irritating action on the stomach, how- 

 ever, it can not be used in this way. Schultzen and Nencki 

 have made some experiments which prove that the products 

 which albumin gives when decomposed by alkalies namely, 

 glycocin, leucin, and tyrosin are excreted as urea when in- 

 gested into the organism the latter less readily than the oth- 

 ers. This suggests that a similar metamorphosis of albumin 

 goes on normally in the body. The liver-sugar question has 

 received its share of attention. Dock has proved that the liv- 

 er can form glycogen (liver-starch) from ingested cane-sugar, 

 even in a few hours. Puncture of the floor of the fourth 

 ventricle causes sugar to be excreted, but no glycogen is 

 formed in the liver. The same effect is produced by curara 

 injections. Hence it might seem that diabetes was due to 

 the direct excretion of the ingested sugar, owing to its non- 

 conversion into glycogen. But as curara causes the excre- 

 tion of sugar when none has been ingested, Dock thinks the 

 muscles themselves must have the power of retaining sugar 

 or glycogen. Wanklyn has found that the ratio of the am- 

 monia evolved from an animal fluid by evaporation, with 

 potassium hydrate at 150 C, is, to that obtained by subse- 



