32i Description of an Invention 



caustic potash. The potash which I employed, melted alone 

 in the same crucible, absolutely remained colourless. 



I did not endeavour to determine the quantities with pre- 

 cisioo, but I am convinced that they were very different. 



This observation agrees with the division established by 

 M. Stengel among meltings, and may lead to exact experi- 

 ments, serving to prove the ingenious conjectures of this 

 metallurgist. 



I have endeavoured in this memoir to prove that the ores 

 of spathic iron have not all of them an uniform composition. 



That the refractory quality of some among them is owing 

 to the great proportion of magnesia which they contain. 



I have endeavoured to explain, by the properties of this 

 earth, the different practices made use of in the iron-works 

 where this kind of ore is melted, and which practices have 

 not been hitherto explained. 



I certainly wish that new observations should confirm my 

 conjectures ; but if it is proved that I am deceived, I shall 

 nevertheless congratulate myself on having called the atten- 

 tion of metallurgists to one of the most important objects of 

 the science to which they belong. 



L. Description of an Invention for elevating and de- 

 pressing Water, applicable to the Use of Canal Locks, 

 and for preventing the usual Waste of Water therein, 

 By Mr. Robert Salmon, of Woburn *. 



SIR, 



_T on the inspection of the Society of Arts, &c. I have for- 

 warded my model, and you herewith receive inclosed a de- 

 scription thereof. The novelty of this mode of bringing 

 into action a considerable force, will, I hope, appear; and 

 I beg leave to observe, that, besides the principle being ap- 

 plicable to locks, it will apply to many other uses where a 

 lift or descent is required. It may also be right to observe, 



* From Transaction* nf Society of Arts, &c. 1806. The society voted Mr. 

 Salmon the silver medal and ten guineas for this improvement, 



that 



