302 



NA TURE 



[January 24, 1901 



properties. This problem, then, will, as soon as possible, 

 be taken in hand. 



Another important task is the testing of steam, gauges, 

 indicator springs and the like ; for this purpose a mer- 

 cury pressure gauge will be provided in the physics 

 building to measure pressures up to twenty atmospheres 

 — the height of the building will not allow more to be 

 measured directly — together with an arrangement for 

 multiplying in a known ratio the pressure measured 

 ■directly. 



Again, gauges of all kinds used in engineering prac- 

 tice will be tested, including the standard screws which 

 the Small Screw Committee of the British Association 

 hope to issue. Another problem which calls for early 

 attention is that of wind pressure on surfaces. 



BUSHY HOUSE 



is becoming more important each day. In the Optical 

 Department photographic lenses are now tested by eye 

 observations only. It is proposed to establish a photo- 

 graphic test, and to include microscope and other 

 lenses. 



It will be seen thus that there is a full programme of 

 work before the staff of the laboratory ; the Committee 

 are anxious to keep in the closest touch with trade and 

 industry, and the Director will welcome any suggestions 

 to secure this end. The laboratory has been established to 

 deal with physical problems bearing on manufacture and 

 commerce ; it can hope to succeed only through the 

 cordia' co-operation of the men who know what those 

 problems are, and who can indicate the lines along which 

 the necessary investigations should proceed ; with their 



assistance it may soon do a national 



work. 



Fig. 2. 



In electricity there is ample scope for work. The 

 magnetic testing of iron for commercial use will be under- 

 taken at once, and there are many forms of apparatus 

 which do not come under the direct cognisance of the 

 Board of Trade Electrical Department for which it is 

 ■desirable to have some recognised test — e.g. condensers, 

 special forms of cells, resistance boxes as distinct from 

 standard coils and the like. A valuable list of measure- 

 ments, by which the work of the Board of Trade Labora- 

 tory would be supplemented and assisted, has been 

 submitted to the committee by Mr. Trotter. 



Optical and thermometric testing is now carried out to 

 a large extent at Kew Observatory, but both these 

 branches of the work can be extended ; the question of 

 the measurement of very high and of very low temperatures 



NO. 163c, VOL. 63] 



THE PRESENT CONDITION OF 



THE INDIGO INDUSTRY. 

 TpOR some time past letters on the 

 ^ subject of artificial versus natural 

 indigo have been appearing in the 

 Times. One by L. J. Harington, which 

 appeared at the end of last month, is 

 of considerable interest, since he writes 

 as a planter of nineteen years' experi- 

 ence. He considers that the days of 

 natural indigo are not numbered, and 

 that the Government of India are not 

 likely to take the advice of Dr. Brunck 

 (Nature, p. iii) and endeavour to 

 grow food stuffs in place of cultivating 

 indigo. He further remarks that 

 " there is so little to choose between 

 artificial and natural indigo that the 

 whole thing is a matter of price, and 

 the victory must go to the one who 

 can afford to sell cheapest." He then 

 goes on to say : " Indigo had always 

 paid, at times well, at other times 

 fairly so, and planters were content to 

 grow and manufacture indigo exactly 

 as their predecessors had done. Then 

 in 1897 the Badische discovery came 

 like a bolt from the blue." This is a 

 rather remarkable admission. Here 

 were men manufacturing indigo, and 

 they had evidently not taken the 

 trouble to ascertain what was being 

 done in the scientific world and by 

 other manufacturers. Were they not 

 aware that so far back as 1880 indigo 

 had been synthetically prepared, and 

 that numerous patents had been taken 

 out ? Certainly the processes had not 

 been commercially successful ; but 

 surely they should have taken warning, and endeavoured 

 to improve their product and to manufacture it more 

 cheaply. 



Mr. Harington says that after the "bolt from the 

 blue" in 1897' the price of indigo steadily fell until 

 1899, when, owing to the bad season, one of the finest 

 crops ever seen in Behar was ruined and the price rose 

 nearly 25 per cent. This naturally gave the producers 

 of artificial indigo their chance, and they were able to 

 offer their product at prices slightly lower than those 

 ruling for the natural article. According to Mr. Har- 

 ington, when synthetic indigo was first placed on the 

 market the average cost of manufacturing Behar indigo 

 was 170 rupees per maund, but that now, owing to more 

 careful working and by sowing only on good lands, it 



