558 



NATURE 



{April 



12, I 



thei classes of substances used stand as follows: (i) bitters; 

 (2) acids ; (3) saline substances ; (4) sweets ; (5) alkalies. 



3. The sense of taste is as a rule more delicate in women 

 than in men (in the case of all substances tried excepting salt). 

 The number of persons experimented upon was hardly sufficient, 

 considering the very striking individual peculiarities met with in 

 the course of our investigation, to permit us to lay great- stress 

 upon the relative averages obtained for the two sexes. We are 

 not inclined, however, to regard the higher degree of sensitive- 

 ness shown in the averages for female observers as accidental, 

 and our confidence in the approximate value of the results is 

 strengthened by the fact that in the two portions into which our 

 data naturally divided themselves, about half the tests having 

 been made at a different time and under different circumstances 

 from the remainder, the averages for each set agreed very well, 

 not only as to the relative sensitiveness to the various substances 

 employed, but also to the relatively higher degree of delicacy 

 exhibited by women. 



4. The ability to detect a dilute bitter is very generally accom- 

 panied by inability to detect a dilute sweet, and vice versd. 



5. The long-continued habitual use of a substance does not 

 seem to influence in any marked way the delicacy of the sense of 

 taste for that substance. Our tests with quinine afforded an ex- 

 cellent opportunity for the investigation of this point, as some of 

 the persons experimented upon had made long continued use of 

 that drug as a medicine. The results obtained were entirely of 

 a negative character. We could discover neither increase nor 

 decrease in the ability to taste the drug on the part of those 

 habituated to its use. 



. Several other questions have been raised but not answered by 

 our experiments. How many, for instance, of these substances, 

 each being diluted in proportion to its effect upon the organs of 

 taste, can be detected if mixed together ? If so mixed, in what 

 order will they be recognized, and will it always be in the same 

 order by different persons? Again, what is the influence of 

 the temperatui-e of the solution upon our ability to taste its 

 ingredients ? 



We deplore the fact that the above tests have not been extended 

 to a much larger number of persons, but a careful study of the 

 results of the limited number of experiments made leads us to 

 believe that they do not differ widely from the probable averages 

 of a much more extended series. E. H. S. Bailey. 



University of Kansas, July 1887. E. L. Nichols. 



The Salt Industry in the United St&tes. 



Having occasion not long since to look up the statistics of 

 the salt industry, I naturally turned to the latest edition of the 

 "Encyclopaedia Brittanica" (vol. xxi.), where the following 

 statement met my eye ; — " The deposits of salt in the United 

 States are unimportant. The country possesses no really con- 

 siderable salt industry, but is supplied so far as interior 

 consumption is concerned to a small extent by brine springs." 



As this did not at all correspond with the knowledge I had 

 gained by a somewhat casual glance over the field, I took pains 

 to look up the subject more thoroughly, and find the above 

 statement so radically wrong that I venture to call your attention 

 to it ; though this I should scarcely have troubled myself to do had 

 it appeared in any publication of less acknowledged authority. 

 To be sure, we have no means of knowing just how great an 

 industry must be to be classed as "really considerable," but by 

 comparing the annual product of the United States with that 

 of other countries we may claim, at least, an attempt at an 

 approximation. 



But first as to the character of the beds in the United States. It 

 is true there are as yet known no beds comparable in depth and 

 extent with those of Barcelona or Galicia, but nevertheless they 

 are amply sufficient to supply all demands for ages. As long 

 ago as 1869, Dr. Sterry Hunt published, in the Reports of the 

 Geological Survey of Canada, results of borings at Goderich, 

 Canada, in which, in a total depth of 1382 feet, six successive 

 beds of salt were passed through, varying in thickness from 6 to 

 34 feet, and aggregating a total thickness of 126 feet. What 

 area is covered by these deposits is yet to be ascertained ; but 

 they are known to extend over Central and Western New York, 

 Northern Pennsylvania, North- Western Ohio, and Southern 

 Ontario. At Warsaw, in New York State, one of the beds has a 

 thickness of 80 feet. The extent of the deposit at Petite Ainse, 

 Louisiana, has also yet to be determined, but a vertical shaft 

 165 f«et in depth lies all the way in solid salt, and does not 



penetrate it. The above, although but two out of many, I 

 mention since they have been known for years, and it would 

 seem Mr. Lyte could have informed himself regarding them had 

 he so attempted. Concerning the many extensive beds in the 

 region of the Great Basin, ignorance is more excusable. Statis- 

 tics showing the annual output of both rock and sea salt will 

 best show the extent of the industry. I give below statistics for 

 1883, 1884, and 1885, taken from " Mineral Resources of the 

 United States," p. 474. One barrel equals 280 lbs. 



Michigan 



New York 



Ohio 



West Virginia ... 



Louisiana 



California 



Utah 



Nevada 



All other States and 

 Territories 



Totals ... 



Barrels. 

 2,894,672 

 1,619,486 

 350,000 

 320,000 

 265,215 

 214,286 



107,143 

 21,429 



400,000 



6,192,231 



Barrels. 

 3,161,806 



1,788,434 

 320,000 

 310,000 

 223,964 



178,571 

 114,285 



17,857 

 400,000 



6,514,937 



Barrels. 

 3,297,403 

 3,304,787 

 306,847 

 223,184 

 229,271 

 221,428 

 107,140 



28,593 



250,000 



7,038,653 



Complete statistics for all countries are not available, and I 

 have to rely to a considerable extent on Encyclopaedias, whose 

 accuracy I now have reason to question. They are as follow: — 



In regard to the above figures, I confess to feeling sceptical 

 save with reference to those of the United States and England. 

 Nevertheless, granting that they do not give the full amounts by 

 one-half, even then the United States stands second in the list 

 of salt-producing countries. 



What, then, constitutes a really considerable industry ? 



George P. Merrill. 

 U. S. National Museum, Washington, D.C., 

 December 3, 1887. 



Force, and Newton's Third Law. 



The point mentioned by " Nemo " in your issue of March 29 

 (p. 511) is undoubtedly one that troubles most students at some 

 stage or other; but there is no room for discussion about it ; the 

 matter lies in a nutshell : a body does not exei't force upon itself. 

 Think, for instance, of a horse and cart. The horse pulls the 

 cart, and the cart pulls back the horse equally ; how, then, can 

 the cart move? The only puzzle lies in the false implication 

 that the cart's pull-back is exerted upon the cai-t. Directly it is 

 perceived that there is only one force acting on the cart, viz. 

 the pull of the horse, no difficulty is felt as to why it moves. 

 The "action" of A is not exerted upon A, but upon B, The 

 "reaction" of B is not exerted upon B, but upon A. The 

 time rate of change of momentum of each and every body is 

 equal to the total force acting upon it. Oliver J. Lodge. 



Grasmere, March 31. 



The New Photographic Objective. 



The letter of Sir Howard Grubb in your issue of March 8 

 (p. 439) appears to make some further explanation desirable on 

 my part. The invention of the new form of photographic ob- 

 jective seems to have been made about the same time in America 

 and in England. An experimental lens of this kind was con- 

 structed by the Messrs. Clark, after consultation with me, in 

 May 1887. The 13-inch lens which they subsequently made 

 upon the same plan was completed on July 8 of that year. My 

 absence during the summer in Colorado, with the intention of 

 selecting a place for the new instrument upon some ^mountain of 

 considerable height, caused me to overlook the account of the 

 English invention in the Observato>y. Since my return, the 

 telescope has been mounted in Cambridge, on the grounds of 



