^luntiii 



FOR GENERAL READERS. 



Vol. II. 



NOVEMBER 2, 1888. 



No. 18. 



CONTENTS. 



PAGE 



Scientific Table Talk 449 



The Respiration of Eats during their 



Winter Sleep ... 450 



The Scaly Amphibia of the Plauen 



Glen {///us.) 451 



Mars and its Canals {///us.) 453 



The Serpent in the Mythology and the 



Worship of Ancient Nations ... 453 



General Notes 455 



The Gorton Boiler {///us.) 457 



'Storage of Material and Force in Plan's 457 

 Natural History — 



Cochineal Insects {///us.) 459 



PAGE 



461 

 461 

 4*1 



Hybernating Dragon Fly ... 

 Batrachia of Southern India. . . 

 The Size of the Cobra 



Reviews — 



Report of the U. S. Commissioner 

 of Agriculture ... ... ... 461 



The Foundation Stones of the Earth's 



Crust 462 



Abstracts of Papers, Lectures, etc. — 



Junior Engineering Society... ._ 464 



Miscellaneous Societies ... ... 465 



The Beating of the Heart 466 



: Australian Association for the Ad- 

 vancement of Science ; President's 



Address ... .. ... ... 467 



Correspondence — 



Totem Clans and Star Worship ... 47 



Recent Inventions ... ... ... 470 



Announcements 471 



Sales and Exchanges ... ... ... 472 



Notices ... ... ... ... ... 472 



Selected Books 472 



Diary for Next Week 472 



Meteorological Returns ... ... 472 



SCIENTIFIC TABLE TALK. 



By W. Mattieu Williams, F.R.A.S., F.C.S. 



The Saturday Review commences an article on the sub- 

 ject of " Adulteration " as follows : " Generally speak- 

 ing, nothing which we eat or drink is what it seems ; 

 everything is unreal and what it ought not to be, from 

 marmalade, in the composition of which the common 

 turnip plays no insignificant part," etc., "etc. 



This statement about turnips in marmalade is so fre- 

 quently repeated, and is actually believed by so many, that 

 a demonstrative contradiction is demanded. Some years 

 ago I tried the experiment of mixing " no insignificant " 

 proportion of turnip pulp with some home-made marma- 

 lade, first using equal weights of. turnip and orange, and 

 found the result most nauseous, the rank turnip flavour 

 growing worse and worse the longer it was kept. I then 

 tried two of orange to one of turnip, then three to one, 

 and finally only tV of turnip — that is, one ounce to the 

 pound — and still the turnip flavour was so evident, both 

 to taste and smell, that such a mixture would be utterly 

 unsaleable. This experiment may be easily repeated by 

 anybody. 



A great number of other alleged adulterations, when 

 practically tested, prove to be equally imaginary. That 

 of iron filings in tea was very popular some years ago, 

 definite assertions as to the quantity thus added being 

 made, commonly about 5 per cent. Grocers were con- 

 victed and fined for selling tea containing such quantity. 

 I wrote to the Chemical News a letter which was pub- 

 lished November 21st, 1873, working out the figures as 

 follows. The price of the cheap teas said to be thus 

 adulterated does not exceed 4d. to 6d. per pound in China. 

 If the Chinaman obtains iron filings at 2d. per pound, 

 his gain by such adulteration would amount to about 

 i'o of a penny per pound, or still less when the cost of 

 labour in mixing is deducted. The total deliveries of 

 black tea into the port of London alone amounted at 

 the time to 160 millions of pounds, of which 140 mil- 

 lions came from China. Adding those to tea-drinking 

 Russia, to America, and the British Colonies, the total 

 exports from China amounted to 400 to 500 millions of 

 pounds of tea per annum. If only 100 millions of pounds 



were thus adulterated (the iron was found in all samples 

 of black tea) five millions of pounds of iron filings would 

 be required annually. How could the Chinaman obtain 

 this quantity of filings ? It should be noted that only 

 very fine filings would answer the purpose, as coarse 

 filings would shake down to the bottom of the chests. 



If the adulteration was perpetrated in England, where 

 is the market ? Where are the waggon-loads of iron 

 filings that would be demanded ? Who collects them ? 

 The quantity produced in each workshop being so small, 

 the collecting of a million of pounds would be a big 

 business. As a matter of fact no market for iron filings 

 exists, except for small quantities used by firework- 

 makers and some other trifling purposes. Nearly all are 

 swept away. 



But there is iron in tea ; it has been found even in the 

 leaves of plants grown under glass at Kew. "The 

 Yellow River " of China is so called because it is tinted 

 with the ochreous earth which constitutes the soil on 

 which most of the Chinese tea is grown, and tea-leaves 

 gathered in dusty weather are liable to be slightly coated 

 with the ferruginous dust from the soil on which they 

 grow, in addition to containing a little iron, which they 

 naturally absorb from the soil. Upon this basis was 

 erected the whole fabric of supposed adulteration. As I 

 showed in the letter above referred to, the colour of 

 black tea is due to the combination of some of the iron it 

 contains with the tanno-gallic acid it also contains. This 

 tanno-gallate of iron is the colouring matter of ordinary 

 black ink. In the dried tea-leaf it exists in an insoluble 

 form. 



The idea of substituting sloe leaves in this country, is 

 equally absurd. Where are the sloe plantations ? If 

 gathered from the hedgerows, where the wild sloe 

 may be found, who are the gatherers ? They should be 

 as numerous and as evident as hop-pickers. 



Within my recollection it was confidently asserted that 

 brown sugar was adulterated with sand. Common 

 sense should have refuted this at once, seeing that every 

 cup of tea or coffee sweetened with such sugar would 

 effect a quantitative analysis by displaying a gritty, in- 

 soluble residue at the bottom of the cup. Plum 

 puddings or any other solid product of cookery in which 



