May 5, 1921] 



NATURE 



297 



Letters to the Editor. 



\the Editor does not }iold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake to 

 return, or to correspond with the writers of, rejected manu- 

 scripts intended for this or any other part of Nature. JVo 

 notice is taken of anortymous communications.] 



A Comparison of British and German Volumetric 

 Glassware. 



The manufacture of volumetric glassware was 

 practically non-existent in this country prior to the 

 war. During and since the war it has been developed 

 on an extensive scale. Unfortunately, many users of 

 volumetric apparatus believe that the accuracy of 

 British apparatus is inferior to that of German origin. 

 From our experience at the National Physical Labora- 

 tory we are in a position to know that apparatus 

 of British manufacture which has passed our tests is 

 at least as good as any similar standard apparatus of 

 German origin. It appeared to be a matter of some 

 interest, however, to ascertain the degree of accuracy 

 of ordinary grade volumetric apparatus. Con- 

 sequently in November last samples of glassware 

 were obtained from seven different London firms. 



Ordinary commercial-grade apparatus was asked for 

 and the purchases were made by a third party, the 

 firms being quite unaware that the apparatus was 

 ultimately destined to be tested at the National Physical 

 Laboratory. The results obtained in the tests on this 

 apparatus are given below. The results marked * 

 relate to apparatus bearing the trade-mark of one 

 or other of the British manufacturers who regularly 

 submit apparatus to the National Physical Laboratory 

 for test. The results marked t refer to two flasks 

 which also bore the trade-mark of a British firm. 

 The remaining results for the November purchase 

 relate to apparatus which had no trade-mark. This 

 was probably mainly British, but some of it possibly 

 of German origin. 



In March last purchases were made in a similar 

 manner, but it was stipulated that the apparatus must 

 be of German manufacture. Of about half a dozen 

 firms visited only two would undertake to supply 

 apparatus of German origin. The results for the 

 apparatus obtained from these two firms are given 

 below, along with the results for the apparatus pur- 

 chased previously : 



tp c.c. Pipettes. N. P. L. limits : — Class A, +0'03S c.c. Class B, +O'o6 c.c. Delivery time, 20-40 sec 



\oc.c. Pipettes. N.P.L. limits :— Class A, ±0-015 c.c. Class B, +003 c.c. Delivery time, 15-30 sec. 



k 



NO. 2688, VOL. 107] 



