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THE POPULAR SCIENCE MONTHLY. 



indicate a quantity of copper less than 0.5 

 milligramme. Mr. Merrick's method con- 

 sists simply in concentrating to a very small 

 bulk the solution suspected to contain cop- 

 per, and then depositing the copper, if pres- 

 ent, upon platinum, by the battery. He uses 

 for a depositing-cell a very small test-tube, 

 on a foot cut off, so as to give a vessel about 

 one and a half inch deep. Into this is intro- 

 duced the solution acidified with sulphuric 

 acid, and a platinum anode and cathode 

 each about an inch long and one-eighth inch 

 or less wide are hung face to face, and 

 very close together ; and, the circuit being 

 completed, very satisfactory deposits of 

 copper are obtained with incredibly minute 

 quantities of the metal. The amounts are 

 determined by the increased weight of the 

 cathode (which is provided with a platinum 

 wire soldered on with gold, by which it can 

 be hooked to a balance) and on the loss of 

 weight of the same after washing with ni- 

 tric acid. The platinum is polished and 

 heated red-hot before the first weighing, 

 and then gently heated before hanging in 

 the solution. The contrast in color between 

 deposited copper and bright platinum is, of 

 course, striking and characteristic. In this 

 way, 0:1 milligramme of copper may be, 

 the author thinks, safely determined ; while 

 for mere qualitative analysis this method 

 may be employed where the amount is even 

 smaller. 



Award of the Blgsby Medal to Prof. 0. 

 C. Marsb. Prof. P. Martin Duncan, Presi- 

 dent of the Geological Society of London, 

 in announcing the award of the Bigsby 

 Medal to Prof. 0. C. Marsh for his services 

 in investigating the paleontology of the 

 Vertebrata, paid a high but well-merited 

 compliment to the learned Yale professor. 

 Said Prof. Duncan : " He has distinguished 

 himself by studying the fossil remains of 

 nearly every great group of the vertebrata 

 from the palaeozoic, cretaceous, and caino- 

 zoic strata of the New World. The field 

 of his research has been immense, but 

 it has been very correct ; and his descrip- 

 tive and classificatory palcontological work 

 indicates his effective grasp of anatomical 

 details, and his great power as a compara- 

 tive osteologist." Prof. Duncan then enu- 

 merated in some details the chief lines of 



research pursued by Prof. Marsh, and was 

 followed by Mr. Hulke, himself a paleon- 

 tologist, who heartily approved all that had 

 been said by the president with respect 

 to the value of Prof. Marsh's services to 

 paleontology. " These," he said, " are so nu- 

 merous and important as to mark an epoch 

 in this line of research. The present rec- 

 ognition of the value of his labors will 

 doubtless prove an incentive to fresh work." 



What is Moderate Drinking.? The ad- 

 vocates of total abstinence from intoxi- 

 cating liquors are wont to condemn even 

 a moderate use of stimulating drinks, on 

 the ground that "moderate drinking is the 

 parent of excessive drinking." The Lancet 

 questions the correctness of this proposi- 

 tion, but in its negative definition of what 

 is meant by " moderate " drinking the vota- 

 ries of Bacchus will find very little comfort. 

 " The man," says the Lancet, " who begins 

 the day with a ' soda-and-brandy,' has very 

 little respect for his constitution, and if he 

 does not alter his habits, they will alter his 

 health. Odd glasses of beer and glasses of 

 spirit in a forenoon do not come within the 

 range of moderate drinking. That is not 

 moderate drinking which adds fifteen or 

 twenty beats to the pulse, or which flushes 

 the face. Finally, all casual drinking is bad, 

 presumably, and not moderate drinking. 

 The system will not receive food merely as 

 a matter of conviviality, at all sorts of odd 

 hours. Still less will it receive with impu- 

 nity drink in this way. Drinking which 

 disturbs sleep, either by making it heavy 

 or by driving it away, is not moderate. 

 Moderate drinking is that which consists 

 with a clean tongue, a good appetite, a slow 

 pulse, a cool skin, a clear head, a steady 

 hand, good walking-power, and light, re- 

 freshing sleep. It is associated with meals, 

 and is entirely subordinated to more con- 

 venient and less objectionable forms of food. 

 That such drinking produces drunkenness, 

 has yet to be proved, as it has yet to be 

 proved to be essential to health." 



Retention of Impressions by tlie Retina. 



Does the retina retain in death the image 

 last impressed upon it? That such is the 

 case has been asserted, but hitherto the 

 evidence has not been satisfactory, to say 



