5o8 



NATURE 



[January 7, 19 15 



The wind channels at the National Physical 

 Laboratory were recently described in Nature, 

 and little need be reproduced of Prof. Zahm's 

 report. He describes the aerodynamic current as 

 the steadiest in the world with limits of \ per cent, 

 in both time and space. The steadiness of the 

 air-flow in the Eiffel apparatus is stated to be 

 2 per cent, in time and space. 



Prof. Zahm claims priority for the use of bell- 

 crank balances for aerodynamical work, and says 

 that he is of opinion that several new types can 

 be devised which shall be equally precise with 

 those at the National Physical Laboratory, and 

 probably more expeditious. Such new types have 

 been in contemplation since first devising- the bell- 

 crank aerodynamic balance in 1902. It is therefore 

 probable that the balance for the wind tunnel of 

 the Lang-ley Laboratory will be of the bell-crank 

 type, but will differ in detail from those in use in 

 Europe at the present time. 



In reference to full-scale experiments, Prof. 

 Zahm considers that the Royal Aircraft Factory 

 most nearly approaches the organisation projected 

 for larg-e-scale work at the Langley Laboratory, 

 thoug^h he excludes the possibility of manufactur- 

 ing aircraft in considerable numbers. He con- 

 siders the outcome of the large-scale experiments 

 at the Royal Aircraft Factory to be the production 

 of a stable, efficient, and safe biplane. Reports 

 from the seat of war add strong support to this 

 view. 



A considerable amount of space in the report is 

 devoted to a description of the apparatus for large- 

 scale experiments at St. Cyr, near Paris, and the 

 remark is made that the relative importance of 

 such large-scale tests as can be carried out on 

 moving carriages, as compared with model tests 

 or full-scale flights with instruments mounted on 

 the aeroplane, has yet to be determined. The diffi- 

 culties of experiment are indicated by the state- 

 ment that the lift measurements on simple lifting 

 surfaces are 5 per cent, in error, whilst the resist- 

 ance measurements are much less accurate. 



It is interesting to note that at the time of the 

 visit, no aerodynamical experiments had been 

 made in Germany other than those at Gottingen, 

 but that arrangements were almost completed for 

 large-scale work at Adlershof, near Berlin. For 

 further particulars reference should be made to the 

 original report. 



CHEMISTRY OF WHEAT AND FLOUR. 



FEWER than ten years ago most millers and 

 bakers would have scoffed at the idea of 

 there being any connection between chemistry and 

 wheat or flour, and even the man of science would 

 have admitted that the application of chemistry 

 to such problems as the cereals presented was 

 in its earliest infancy. Progress, however, has 

 come rapidly and not only is the actual knowledge 

 in the field now very considerable, but it has been 

 already of the utmost value when applied in prac- 

 tice, so that scientific milling as well as scientific 

 baking have made great strides. 



NO. 2358, VOL. 94] 



It is safe to forecast that chemistry is destine*' 

 to play as important a part in the manuf actus 

 of flour in the future as mechanical science ha- 

 done in the past, and it is satisfactory to note 

 that there is every indication that Britain is more 

 than prepared to hold her own in this development. 

 Flour is primarily a starchy material, but those 

 characteristic properties which enable it to be 

 I made into bread are due almost entirely to the 

 I presence of some 10 per cent, of nitrogenous 

 I material — the gluten. Consequently, from the 

 I point of view of the miller and the baker, gluten 

 j is the all-important constituent of flour. Some- 

 what irrationally gluten has come to be regarded 

 I as such also by the would-be food expert, who 

 overlooks the fact that bread is eaten primarily, 

 not as a source of protein, but as an easily 

 digestible, attractive form of starch. The man in 

 the street properly regards bread as equivalent to 

 rice, potatoes, or the like, rather than as a sub- 

 stitute for meat; it is, therefore, not surprising 

 that the would-be agitators have failed. 



Gluten, which is readily obtained from a piece 

 of dough by washing and kneading it in a stream 

 of water until the starch has been removed, is 

 a light brown material which has considerable 

 elasticity. 



From the chemical aspect, gluten is a mixture 

 of several proteins, of which two only are of 

 importance so far as its bread-making properties 

 are concerned. These are named gliadin and 

 glutenin, and they are apparently chemical enti- 

 ties so far as this description can be applied to 

 any protein. Gluten is characterised by the pro- 

 perties of ductility and tenacity so that in dough 

 it can entangle air in its cavities, which swell 

 during fermentation and still more when heat is 

 applied. 



Wheat grown in different parts of the world 

 is far from being always the same nor does the 

 flour derived from it give the same type of bread. 

 It has long been known that certain types of. 

 flour give a large, well-aerated loaf, generally 

 white in colour, and very palatable, whereas other 

 types give a small loaf which is close in texture, 

 dull in colour, and of a stodgy character. Such 

 flours are distinguished as strong and weak and 

 are valued with a difference of several shillings 

 a sack in their price. It has been attempted to 

 express this difference between strong and weak 

 wheats by analysis, and from time to time strength 

 has been correlated with high nitrogen content or, 

 what amounts to the same, a high percentage of 

 gluten, or again to a certain ratio of glutenin to 

 gliadin. Though there is a rough parallelism 

 between strength and these factors, it is in no 

 case absolute, so that no one of them could be 

 said to be the cause of strength. Indeed, the 

 solution of the question has been found in quite 

 another direction. 



Gluten prepared from the strongest flour, when 

 carefully cleaned by repeated washing in distilled 

 water, loses its properties ; it has neither ductility 

 nor tenacity and partly dissolves in the water. 



