﻿Protection of Brass Weights, 



949 



as a result I find that the original relative values of the 

 whole set of: weights are still retained ; no re-adjustment 

 has been required. These observations and conclusions are 

 also borne out by the fact that the uniform and somewhat 

 pleasing bronze-like tint acquired by the weights during the 

 treatment is still to a large extent almost unchanged. 



To obtain indubitable evidence as to the intrinsic value of 

 the method described above, the plan was lately tried with 

 other weights but without success. And here we may observe 

 that owing largely to the admixture of one or more 

 sulphur compounds, the quality of the present day coal-gas 

 is very different from that which formerly obtained, and 

 experimental work showed that to this fact must be attributed 



Fig. 1. 



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my non-success with the second set of weights. The diffi- 

 culty which thus so unexpectedly arose, has now been over- 

 come by a method which for convenience and effectiveness 

 leaves but little to be desired. The new plan is as follows : — 

 A "vitreosil" crucible having a capacity of 50 c.c. is 

 loosely charged with asbestos fibre to the depth of about 

 half-an-inch, as shown in the figure. A lid /, also of vitreosil, 

 is inverted and placed upon the fibre ; on this lid are 

 arranged triangular-wise three pointed fragments of porcelain 

 or fused quartz for supporting the weight w. The weight 

 having been cleaned and polished and evenly covered with 

 linseed oil, which is applied with the finger and thumb, is 

 stood within the crucible, as indicated in ihe figure; the 



