54 KANSAS CITY REVIEW OF SCIENCE. 



troduced and in use upon some of our Liverpool steamers represent several differ- 

 ent makes, the object in this seeming to be to test the comparative merits of each. 

 There is a very sharp competition between the representatives here of the some 

 half a dozen leading makes of refrigerators used in transportation, each naturally 

 claiming that his own is, upon the whole, the best system, and seeking for it 

 some advantage. 



The ocean voyage, even from this port, is so much longer than the inland 

 journey, and so much more risk is involved on shipboard as to delays and other 

 causes, that extra caution is required of shippers, and the best possible refrigera- 

 tor arrangements demanded. Up to this time, ice has been the only agent used 

 on cars and steamers to secure a preservative temperature. Chemical methods, 

 however, have been under private experiment by different parties the world over. 

 There are also at least two different parties in this city now engaged in experi- 

 menting on a large scale with systems of producing cold, without ice and without 

 chemicals, by — as it were — pumping the caloric out of the refrigorating chamber. 

 The parties referred to as engaged in these experiments have made substantial 

 progress in the use of their machinery, but the matter has not yet sumcently ma- 

 tured for public exhibition. The purpose in the new system is to run the ma- 

 chinery by power to be obtained from the steamship's boilers. 



Until the new plan is open for thorough public examination as to its work- 

 ings, it would be premature to announce anything more than that those engaged 

 in the matter are sanguine, from what they have already accomplished, that they 

 will secure a practical success. Should the anticipations of those working on the 

 new system be realized, quite a revolution would take place in the method of re- 

 frigerator transfer, bom on rail and ocean, as well as in cold warehouse storage 

 on a large scale. — Boston Journal of Commerce. 



NEW INSTRUMENT TO DETERMINE THE PRESENCE OF METALS 



IN ORES. 



At a recent meeting of the Philadelphia Academy of Natural Sciences, Prof. 

 George A. Koenig, of the University of Pennsylvania, exhibited his recently 

 invented " chromometer," an instrument designed for the purpose of making 

 exquisitely delicate determinations of the presence of certain metals in ores. It 

 is based upon the optical fact that complementary colors will extinguish each 

 other if mingled in proper proportions \ for instance, if to a green solution a red 

 solution be added, the liquid, if the proper conditions be complied with, will 

 become colorless. The speaker had applied this principle to the colors which 

 certain metals, as iron, manganese, copper, etc., produce when fused with borax, 

 which is the only chemical used in this method of analysis. He prepares such 

 glasses or beads containing known quantities of a metal in one hundred parts, 

 and observes how thick a glass of the complementary color must be to produce 



