December 24, 1891] 



NATURE 



^11 



lime ; if there be more than sufficient to satisfy all the lime, the 

 remainder is calculated to carbonate of magnesia ; if there be 

 too little, however, the remaining lime is combined with sul- 

 phuric acid ; any remaining sulphuric acid is calculated to sulphate 

 of magnesia, and so on ; the order in which the bases and acids 

 are taken being therefore as follows : — 



Lime, Carbonic acid, 



Magnesia, Sulphuric acid, 



Soda. Nitric acid. 



Hydrochloric acid. 



Now, although this is the usually accepted and conventional 

 method of reluming an analysis, there is no doubt that the 

 assumptions it involves are altogether arbitrary, illegitimate, 

 and unscientific. The only scientific method of returning a 

 water analysis is to represent (in parts per 100,000 ; not in 

 grains per gallon, as the atrocious English system of weights and 

 measures generally compels us to) the constituents af/Mrt//j'/t>««rf; 

 as, for instance, 



CaO ; MgO ; COj ; NjOs ; CI ; &c. 

 This is all that an analyst is entitled to say, and this much is 

 certain : when we proceed to combine the constituents, we are 

 dealing in conjecture. 



Unfortunately, however, it seems to be a "law of Nature" 

 that those classes of the community who chiefly require the 

 services of analysts are absolutely ignorant of the merest rudi- 

 ments of chemistry ; the consequence is that if any analytical 

 purist endeavours to reform upon the conventionally established 

 procedure, and to return a certificate of analysis in a scientific 

 manner, his clients are up in arms at once, and indignantly de- 

 mand what he means by sending them such a nonsensical rigmarole. 



Thus far, then, we are helpless ; but it is most undesirable 

 that this conventional procedure should be adhered to whenever it 

 is possible to substitute the scientific (as in an analysis of purely 

 scientific interest). 



" R. B. H. " asks what salts really exist in solution. 



According to Ostwald and others, no salts at all if the solution 

 be dilute enough, but only dissociated ions with electrical 

 charges. But whether this theory be correct or not, it is im- 

 probable to the last degree that an analysis represents the salts 

 actually present. The indeterminateness of the problem is clearly 

 shown by the fact that from the same solution either sodium 

 chloride and magnesium sulphate, or sodium sulphate and mag- 

 nesium chloride, may be obtained, according to the method of 

 crystallization adopted. Even supposing that Ostwald's theory 

 be incorrect, and that not ions but salts exist in solution, and 

 that these different results be due to double decomposition 

 occurring in one case, it would be a gigantic assumption that 

 we can definitely show the exact natural distribution in a 

 complicated solution containing eight or ten constituents. 



If " R. B. H." wishes to see an account of how acids and 

 bases distribute themselves in a simple solution, he may consult 

 Ostwald's " Outlines " (p. 338, &c., English translation), and 

 also the discussion on avidity in Lothair Meyer's " Modern 

 Theories of Chemistry " (472-87). F. H. Perry Coste. 



7 Fowkes Buildings, Great Tower St., E.C., Nov. 28. 



I AM much indebted to Mr. Perry Coste for his clear and 

 candid answer to my question. It is exactly the answer which 

 I anticipated. The actual facts esta'olished by analysis are too 

 often forced, by the arbitrary assumptions of the analytical 

 chemist, to yield unwarrantable conclusions. 



The reason given is, that "the people love to have it so." I 

 had hoped that chemists could give some better grounds for 

 their proceedings. They bring to mind the. words of the old 

 prophet : " A wonderful and horrible thing is come to pass in 

 the land ; the prophets prophesy falsely," . . . for "my people 

 love to have it so ; and what will ye do in the end thereof? " 

 Surely we may henceforth claim, in the interests of truth or 

 (which is the same thing) science, that chemists will give us in 

 every case the actual facts obtained by analysis ; and if they 

 proceed further for the sake of the prejudices of the ignorant, 

 they will at least warn them that such further inferences are not 

 trustworthy, and have only a very moderate amount of prob- 

 ability, if they can even lay claim to any probability at all. 



I speak feelingly, because I have had occasion to examine a 

 great number of analyses of water from the chalk of the London 

 Basin, telling me, in most cases with a " cocksureness " which 

 has amazed me, what salts, and what amount of them, these 

 waters contained, and these, for purposes of comparison, I have 



NO. II 56, VOL. 45] 



had painfully to reduce back to the real facts from which they 

 were derived. 



I am quite prepared to believe that the investigations of 

 Ostwald and others as to solutions show that salts as such do 

 not exist in these waters at all, and that the relations of acids 

 and bases in such cases are variable with the physical condition 

 of the water. As an instance which has come under my own 

 notice, it was reported by competent chemists, with reference to 

 water from a deep well in Harrow, in which an unusual quantity 

 of magnesium and sulphuric -acid was found, that at 60° F. its 

 hardness was 10° "4 (grs. per gall.) ; that, mixed with an equal 

 quantity of distilled water, its hardness rose to 24° : while at the 

 temperature of 158° it rose to 26° "5. I suppose that a chemist 

 would hardly attempt to assign with much confidence what 

 exact changes in the relations of the dissolved constituents 

 would produce these and similar results. All the more reason, 

 then, why analysts should limit themselves to statements which 

 they can vouch for by direct observation and the balance. 



My remarks having extended beyond a mere question, I think 

 it best to sign myself in full, Robert B. Hayward. 



Peculiar Eyes. 



Mr. Shaw's case is by no means so peculiar as he supposes. 

 I imagine that everyone who has had to do with experi- 

 mental questions of physiological or psychological optics has 

 found it to be rather the exception than the rule that an investi- 

 gation of his reagents' eyes has shown their perfect equality — as 

 regards "long" and "short" sight, colour sensitivity, and 

 sensitivity to light. The common preferential use of one eye 

 explains a good deal (cf., e.g., Aubert, " Physiol, d. Netzhaut," 

 p. 18; Schon, Arch. f. Ophthalmologic, xx. 2, p. 271). Mr. 

 Shaw may also be colour-blind in one eye ; the perception of 

 colour difference alone is no criterion. I find it safest to employ 

 the wool, spectrum, and coloured-card tests in combination. 



Animals (with the exception of the very highest) have nor- 

 mally a so restricted binocular vision that they need not be 

 taken into account. 



It may be interesting to note that a like difference of sensa- 

 tional capacity exists between the two ears. A tuning-fork held 

 to one ear may, quite normally, drown a tone-sensation which is 

 half a musical tone deeper or higher than that excited by the 

 same fork in the other ear. E. B. Titchener. 



P.S. — I discovered the very considerable inequality of my 

 own eyes quite accidentally in my sixteenth year. 



Alleged Pseudopodes of Diatoms. 

 Will you allow me to express my concurrence in your 

 criticism (p. 140) on Mr. Grenfell's paper on the occurrence 

 of pseudopodia in the Diatomaceous genera Melosira and Cyclo- 

 tella? I express no doubt on the accuracy of Mr. Grenfell's 

 observations, the knowledge of which I have derived from his 

 paper in the Quarterly Journal of Microscopical Science, and 

 from his verbal description at a meeting of the Linnean Society ; 

 but I do desire to enter my protest against the use of the term 

 "pseudopodia" for the protoplasmic filaments observed by 

 him. According to the accepted meaning of this term, it is^ 

 applied to masses of protoplasm which are in organic connection 

 with the protoplasm of the body of the organism, and which are 

 retractile. I understand Mr. Grenfell that he is unable to affirm 

 either of these facts with regard to the structures observed by 

 him ; and, until this is done, the application to ihem of the 

 term " pseudopodia " appears to me to involve a begging of the 

 question at issue, and a needless and regrettable confusion \n 

 terminology. Alfred W. Bennett. 



Intelligence in Birds. 



Under this head Mr. Wilkins, in your last impression (p. 

 151), speaks of Podoces panari hiding food in the sand. I have 

 a fox-terrier puppy which was taken from its mother when about 

 seven weeks old, and sent to me. I have no other dogs, nor 

 has he seen any dogs, but he buries bones in the garden with 

 great skill, digging a hole with his fore-paws. He puts in the 

 bone, and carefully pushes it down with his nose, and then, 

 covers it with garden soil, which is pushed in with his nose. 

 The work is very carefully and elaborately well done. 



I have had, at various times, very many dogs of all kinds and 

 ages, but I never saw so young a puppy bury bones, or any dog 

 do it so well. It is an admirable example of pure heredity. 



Norfolk Street December 19. JOE. 



