PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 555 



much gearing, this engine answered a good purpose. It has no 

 valves, and does not require an educated engineer to run it. At 

 present we estimate the value of an engine by the proportionate 

 quantity of fuel consumed ; and by this standard all reaction 

 engines will be condemned. 



The chairman presented the following scientific items : 



New Process for Obtaining Heavy Hydro-carbons. 

 Mr. James Young, Jr., of Limcfield, Great Britain, has patented 

 a process for distilling either crude or partially rectified hydro- 

 carbons under pressure, by which heavy oils originally operated 

 on are converted into oils of lower specific gi-avity possessino- a 

 higher commercial value. The process is carried on in an oi-di- 

 nary steam boiler, without tubes, under a pressure of about twenty 

 pounds to the square inch. 



New^ Mineral froji Greenland. 

 Prof Shephard, of Amherst College, has recently analyzed a 

 new mineral sent to him by G. Hagemann, chemist to the ^atroua 

 Chemical works, Allegany county, Pa. It was found at Arksut- 

 fiord, Greenland, in seams or veins, from one third to half an inch 

 in thickness and generally having ciyolite {alam-sodimeaf) closely 

 adhering to its sides. Its color is ochre or wax-yellow, with a 

 a foint tinge of green. The hardness of several specimens lano-ed 

 froau 3. to 3.5, and their specific gravity from 2.59 to 3.60. The 

 mean percentage of their components are — aluminum, 12.06* 

 iron, 5.96; calcium, 11.18; magnesium, 2.30; sodium, 8.45; fluo- 

 rine, 40.30; silicon, 7.79; water, 10.44; insoluble portion, 1.08. 

 The mineral contains a trace of phosphoric acid. Its most re- 

 markable feature is the number of metals found in connection 

 with fluorine. 



Minerals from South Hampton Lead Mine. 

 Prof. Shephard has also lately described two minerals as rare 

 products of this mine. The first is scheelite, or tungstate of lime, 

 and the second cotunite, or chloride of lead, consisting of crystals 

 bearing the form of right rectangular prisms, without transparency, 

 and perfectly milk white. 



An Improvcd Method of Producing Oxygen. 

 Messrs. Marechal and Fessie du Montay, of Mentz, France, have 

 patented a new process for separating oxygen. They state that 



