April 12, 1889.] 



SCIENCE 



275 



that they have not undergone the pressure to which the coal-beds 

 were subjected, although, as in the case of the coal, the wood of 

 which they were formed grew on the spot now occupied by the 

 beds or seams. The other theory is, that the wood was washed 

 down by the rivers from mountainous forest regions, and deposited 

 in quiet bays of the river, where it iinally decomposed, and formed 

 the lignite of to-day. 



The following are various analyses of lignite in its manufactured 

 form, after having been dried and pressed by machinery, but with- 

 out the addition of any foreign matter. Indeed, such is never 

 added, nor is it necessary, the lignite containing within itself all the 

 properties necessary for making it into a cleanly, cheap, and effi- 

 cient combustible. The similarity of these lignite briquettes to 

 wood as regards their heating effects, and the ashes left, will be 

 noticed in the analyses. 



Analyses of Lignite Briquettes.'^ 



which is contained in it. The pressure to which the lignite is sub- 

 jected in order to form it into briquettes is enormous, and at the 

 moment of compression it develops very considerable heat ; so 

 much so, that the hand can barely support the temperature of a 

 newly formed briquette. Supposing for a moment that absolutely 

 dry lignite were fed into the press, as indeed was first done : the 

 ■result would be that the heat developed would be so intense as to 

 carbonize the resin, and the briquette would have no consistency 

 or solidity, but would crumble to pieces. 



In order to obviate this, numerous series of experiments have- 

 proved that the lignite, as it enters the press, must contain eigh- 

 teen per cent of water, and that this amount of water is sufficient 

 to so modify the heat as to prevent the carbonization of the natural 

 resin, allowing the resin to attain to a sticky state only. This, 

 combined with the force of the blow, forms a solid briquette with 

 a polished surface, which does not soil the hands, and which is not 

 easily broken. A constant stream of cold water is kept in circula- 

 tion around the press, so as to cool it as much as possible. The 

 briquettes, as they leave the machine, are steaming ; and the blow 

 given to the succeeding briquette is utilized to impel those which 

 have preceded it, straight into the railway- wagons, along channels, 

 formed of wood, but having at the bottom two iron rails to dimin- 

 ish the friction. By this means hand-labor is avoided for the 

 transport, and the lignite is not touched from the time it enters the. 

 mill in the raw state until it enters the railway-wagon and is sent 

 off to the consumer. 



The briquette industry is increasing from year to year, the ex- 

 isting works are putting up additional presses to increase their 

 output in accordance with their increased orders, while one or two 

 new companies have recently started, and are in a fair way to suc- 

 cess. 



Owing to the great thickness of the bed, the working expenses 

 are very low ; and, when worked in the open, the raw material can 

 be delivered at the works for seven pence per ton. No explosives 

 are necessar}', and as a rule the lignite is loaded direct at the work- 

 ing faces into the wagons of a wire-rope railway, which convey it 

 to the mill. 



In some cases, as at Honem, near Cologne, the workings are all 

 under ground, owing to the great thickness of the layer of gravel 

 which covers the lignite. The method pursued in these cases for 

 working the lignite is precisely similar to the "pillar and stall" 

 system adopted in collieries. Great chambers are cut in the lignite, 

 and supporting pillars are left. The proportion which can be ex- 

 tracted by this means is about two-thirds of the mass. The sur- 

 face of the ground above the workings sinks and cracks, and has 

 to be made good, even at considerable cost ; so that, whenever 

 possible, the open system should be adopted. 



The lignite rests in some cases upon a bed of pure bluish-white 

 clay, as at Kalscheuren, and in others upon a bed of white sand. 

 In either case the material is utilized. The clay makes beautiful 

 white ornamental bricks and piping, while the sand finds a ready 

 sale for a multitude of purposes. At Herzengorath the lignite 

 rests upon this bed of sand, the sand itself being occasionally hard, 

 and in thin beds of friable sandstone. At this mine the concession 

 is surrounded by the collieries of the Aix-la-Chapelle basin ; but as 

 the uses for the two kinds of fuel, coal and hgnite, are so different, 

 the competition is not dreaded, the more especially as the coal can- 

 not be burned in the stoves as at present used for burning wood ; 

 and it is as a substitute for wood, which is largely used as fuel on 

 the Continent, that briquettes of lignite find especial favor. 



The great difficulty which stood in the way of the utilization of 

 the raw lignite consisted in the necessity for rapidly and economi- 

 cally driving off the excess of water it contained, and in doing this 

 in such a manner that the quantity left could be easily controlled 

 and regulated. Absolute dryness is by no means necessary, nor is 

 it aimed at, and for the following reason. The lignite, like the 

 wood of which it is composed, contains a certain amount of resi- 

 nous matter; and the secret of the compressing of lignite into 

 briquettes, and of their cohesion in that form, is this very resin 



^ The analyses were made by a qualified chemist of Cologne. 



THE CHINCH-BUG IN ILLINOIS. 



The economic entomology of Illinois has been distinguished^, 

 during the last four years, by the longest period of continuous 

 chinch-bug devastation known in the history of that insect ; but, as 

 evidences of the disappearance of this outbreak began to accumu- 

 late last fall, it is perhaps not too soon to write its history. 



Mr. S. A. Forbes, the State entomologist, states that its begin- 

 nings were apparent in 1885, when noticeable injuries to corn were 

 reported from ten counties of southern lUinois ; in 1886, thirty 

 counties of that region were seriously damaged, Washingtoni 

 County (about the centre of destruction) being perhaps worst in- 

 fested ; in 1887 the loss was severe in thirty-eight counties of the 

 southern district, and very noticeable in thirty-seven others of 

 northern and western Illinois ; while in 1888 small grain and corn 

 were heavily infested throughout all the southern counties, favor- 

 able weather alone enabling the crops to withstand the injury bet- 

 ter than the year preceding. The attack was now considerably." 

 diminished in the centre of the affected area ; but farther to the 

 east, in Clay, Richland, and Crawford Counties, it was much 

 heavier in the beginning of the season than the preceding year, its 

 force decreasing, however, with the disappearance of the first genera- 

 tion. On the extreme southern borders of the State, on the other 

 hand, it continued with undiminished severity, the damage done 

 in 1 888 being greater than that in 1 887, — greater in Pope and Pulaski 

 Counties than ever before since their settlement. There was thus- 

 apparent a wave-like propagation outward from the centre above 

 mentioned, the crest of the wave of increase requiring two years to 

 pass from Washington County to the Ohio River. A similar grad- 

 ual increase northward was demonstrated by a comparison of the 

 numbers of chinch-bugs in the early spring of 1887 with those of 

 the summer and fall, in the counties of Montgomery, Christian, and 

 Shelby. 



The recent wide-spread appearance of three destructive conta- 

 gious diseases of the chinch-bug, and a consequent diminution of 

 its numbers, make it seem at last unlikely that any extraordinary 

 loss will follow this year in the territory which has been so long 

 infested. 



From the observations and studies reported, it appears that 

 severe drought in the middle and latter part of the summer may 

 diminish the number of the chinch-bug by lessening the food-supply 



