MINERAL OILS 245 



dolerite, frequently enclosing blue masses of the mineral called Hauyno. The Rhenish 

 millstones are sent down the Ehine to Holland, and were formerly imported into 

 this country under the name of ' Dutch blues.' 



IVIII.I.STONE GRIT. A geological term applied to a series of coarse sand- 

 stone rocks, belonging to the Coal-measure formations. ' The term gritstone is 

 perhaps most applicable to the harder sandstones, which consist most entirely of 

 grains of quartz most firmly compacted together, by a purely siliceous cement. The 

 angularity of the particles cannot be taken as a character, since the rock commonly 

 called millstone grit is generally composed of perfectly round grains, sometimes as 

 largo as peas, and even larger ; the stone then commencing to pass into a conglome- 

 rate.' Jukes. 



IKXNERAI, AI.ICAX.I. Soda was formerly so called. 



IVUHTERAI, CA3CTDI.ES. See CANDLES. 



ZVXXNERAI. CARBON. See ANTHRACITE. 



IVZHCTERAIi GREEN. Scheele's Green. Arsenite of copper. See SCHEELE'S 

 GREEN. 



IVXINERAXi OILS. Several hydro-carbon compounds are known under this 

 name. Generally it is applied to petroleum, and other fluid hydro-carbons which issue 

 from the earth. These will be described under the several heads of NAPHTHA ; PETRO- 

 LEUM ; SHALE OIL. 



Lately the mineral oils of Puxiere La Grose and Cordessa have been attracting 

 attention. A few words on those will not be out of place here. They have been 

 examined by Joffre in order to ascertain in what points they differ from the petroleum 

 of America. These oils, obtained by distilling bituminous schists, present at first 

 sight a close analogy with the petroleums. They agree very closely in colour, fluidity, 

 specific gravity, and in boiling point. But on the application of certain reagents a 

 difference is at once recognised. The American petroleums, composed of hydro-carbons 

 of the general formula C"H'- n + -, are not attacked by fuming sulphuric acid, and niono- 

 hydrated nitric acid does not form with them nitro-compounds. On the other hand, if 

 oxir mineral oils are treated with the former of these agents, about the half is absorbed. 

 If they are acted on by the second, about the half also is attacked with formation of 

 nitro-compounds. These oils, therefore, are composed of a mixture of several bodies, 

 some of which resist sulphuric and nitric acids while the others are attacked by them. 

 Both these portions have been studied. The oils were first purified by rectification 

 over sodium ; and they were then divided by fractional distillation into several groups 

 according to the boiling-point. The portion not attacked by fuming sulphuric acid 

 presents all the reactions of the saturated or formenic hydro-carbons, C n H 2n + 2 . It 

 resists the action of the most energetic reagents. Neither fuming nitric acid nor a 

 mixture of nitric and sulphuric acids attacks it in the cold. At a boiling heat, how- 

 ever, it is attacked, under formation of acid products which remain dissolved in the 

 excess of oil. The boiling-points and specific gravities correspond with those of the 

 saturated hydro-carbons. Elementary analysis gives results which point to the general 

 formula C"H 2n + 2 . This part of the mineral oils, is therefore, formed of saturated or 

 formenic hydro-carbons. They seem either identical or at least isomeric with those 

 which Pelous and Cahours extracted from the American petroleums. By acting upon 

 portions of the oil with more or less elevated boiling-points each of the hydro-carbons 

 of the saturated series is obtained, from the hydride of octyle C 8 H, to the hydride of 

 myristyle C 14 H S0 . In the portions which distil over at the end we find the hydrides 

 of pentadecyle C IS H 32 , of hexadecyle C 16 H S| , and of heptadecyle C 17 H 36 . The propor- 

 tion of the saturated is about 50 per cent. The portion attacked by acids consists of 

 hydro-carbons of the ethylenic series C n H 2n , mixed with a certain quantity of hydro- 

 carbons still less hydrogenised. These oils contain neither benzole nor naphthalin. 

 At first sight we might be surprised at the absence of the two bodies so generally met 

 with among pyrogenous products. But on further reflection we cannot help admitting 

 that this is quite natural. The manufacturer of mineral oils seeks to distil the schists 

 at the lowest possible temperature in order to avoid the formation of gas and to secure 

 the largest possible yield of oil. 



The following facts cannot be too widely known : 



A number of patents have been taken out in different countries for 'inexplosivo' 

 gazoline, naphtha, and benzine. Oils of this nature, quite as dangerous as they were 

 originally, before the patented treatment, are sold under such names as ' liquid gas,' 

 ' Aurora oil,' ' safety gas,' ' puroline,' ' petroline,' ' black diamond,' ' septoline,' &c. 

 They are mere mixtures of the ordinary light explosive oils, with roots, gums, barks, 

 and salts. The following are some of the mixtures, as recorded in the Patent List 

 of 1866: 



No. 57,095. Gazoline, 40 gallons ; gum olibanum, 1 Ib. ; cascarilla bark, Ib. ; 

 lichen, (probably Iceland moss), Ib. 



