MISCELLANY. 



375 



exposure to weather is considerable, far 

 greater, indeed, than is generally known. 

 The results of his analyses show in some 

 cases a total loss in weight of a specimen, 

 from this cause, amounting to 33.08 per 

 cent,, while its deterioration in quality, for 

 purposes of fuel or gas-making, reached a 

 still higher figure. This change consists 

 in a slow combustion, in which the vola- 

 tile constituents which are most valuable 

 combustible elements are gradually elimi- 

 nated, while the relative proportions of 

 carbon-ash and sulphur are comparative- 

 ly augmented. It might be expected, now 

 that the nature of this change is indicated, 

 that anthracite (which has already gone 

 through a very similar process in becoming 

 what it is by the loss of its bituminous mat- 

 ter) should suffer least of all coals from this 

 action, and the result of analysis shows this 

 to be the case. The density and compact- 

 ness of this variety, aside from its chemical 

 character, protect it in no inconsiderable 

 degree. The cannel coals rank next in their 

 power to resist deterioration from this 

 source, while the bituminous varieties are 

 the most susceptible. The experiments of 

 Dr. Yarrentrapp are of such direct and 

 practical importance that all who are en- 

 gaged in the mining, transportation, storage, 

 or consumption of coal, can study them with 

 profit. It appears from accurate tests of a 

 number of samples before and after expos- 

 ure, that all the valuable properties of the 

 coal had deteriorated. The coking quality 

 of the weathered coal diminishes with its 

 gas-yielding quality, the author informing 

 us that a sample of coal, yielding when 

 freshly mined a firm, coherent coke, after 

 eleven days' exposure yielded a coke of no 

 coherence, and in all the samples tested the 

 rule was absolute that the longer the coal 

 had been exposed the greater was the infe- 

 riority in the quality of the coke it pro- 

 duced. The gas-yielding quality decreased 

 in one instance 45 per cent., and the heating 

 power 47 per cent. ; while the same sample 

 under cover lost in the same time but 24 

 per cent, for gas purposes, and 1 2 per cent, 

 for fuel. These experiments go far to ex- 

 plain the almost universal inferiority of the 

 Black or waste coals in heating power when 

 prepared for burning, even though some 

 combustible material like pitch or tar is 



used in their cementation. It indicate!!, too, 

 the imperative necessity of keeping coals 

 amply protected from the deteriorating ac- 

 tion of the air and moisture, by keeping 

 them constantly dry and under cover. 



Anecdotes of RatSi A gentleman, who 

 has passed many years of his life at St. 

 Helena, told me lately several stories about 

 rats, so curious that I thought them wor- 

 thy of record. He said that at one time 

 the common brown rat was extremely com- 

 mon all over the island, in fact, a per- 

 fect pest; and, to avoid its attacks, his 

 father had constructed a large store, rat- 

 proof; i. e., a rat once in could not get 

 out again. A number, however, came in 

 with produce and goods from the ships, 

 and bred there. Around this store were 

 Venetian blinds to the windows, and one 

 day one of his men, when it was rain- 

 ing, watched a rat sitting on the Venetian, 

 and putting out his tail to collect on it the 

 drippings of wa'ter at the edge ; he then 

 withdrew it and licked it. The servant told 

 his master, who immediately understood 

 that the rats could get no water inside the 

 store, and therefore directed that a butter 

 firkin should be cut down to four or five 

 inches, and in the top a large circular wire 

 rat-cage trap should be fixed. Several small 

 planks were placed for the rats to get up to 

 the entrance to the cage, which exactly 

 fitted the firkin. No food would have in- 

 duced the rats to enter the trap, but water 

 did, and many were thus captured. When 

 caught they were given to the dogs; but 

 there was one rat which would not leave the 

 trap for many days. He was well identified 

 day by day, till, becoming incautious, he 

 leaped down, and was immediately killed. 

 There is one peculiarity with these rats, viz., 

 their very often building or making their 

 nests in the trees. I have in India several 

 times found rats'-nests in trees; but then 

 they have always been stolen nests, such as 

 deserted abodes of the squirrel or sparrow ; 

 but here my friend, who is no naturalist, 

 tells me that they construct them principal- 

 ly of fir spines, on the ends of the boughs, 

 some twelve or fifteen feet from the ground, 

 in the commoTi fir-trees. The spots selected 

 are just where the overlapping bough near- 

 ly meets the lower one. He said that all 



