7H 



THE POPULAR SCIENCE MONTHLY. 



low soap resin is added. Soft soap is pre- 

 pared from fatty substances, with potash. 

 Cocoanut-oil soap has tlie advantage of being 

 usable with sea-water, and is often called 

 marine soap. Caibolic-acid soap contains 

 about two per cent of carbolic acid, and has 

 antiseptic as well as washing properties. 

 In toilet soaps, as in old brown AVindsor, 

 when they are kept for a long time, the 

 soda is influenced by the air and has its 

 strong properties neutralized. Then it is 

 remelted and stored up again, and remclted 

 a second time, when it becomes soft and 

 tender ; but the toilet soaps of the present 

 are not always given time to age. Pears's 

 Boap is ordinary soap of good quality, cut 

 into shavings, dried, and treated with alco- 

 hol. The alcohol evaporates and leaves the 

 transparent soap. The treatment has the 

 effect of taking all the free soda out of the 

 mixture. 



Genesis of " Original " Rocks.— Dr. T. 



Sterry Hunt gave, in the British Association, 

 a concise account of his theory of the gene- 

 sis of the various groups of original or non- 

 elastic rocks, which he classifies on the basis 

 of their gcognostic relations as indigenous, 

 exogenous, and exotic masses. The super- 

 ficial portion of a cooling globe, consolidat- 

 ing from the center from a condition of 

 igneous fusion, he conceived to have been 

 the protoplasmic mineral matter, which, as 

 transformed by the agencies of air, water, 

 and internal heat, presented a history of 

 mineralogical evolution as regular, as con- 

 stant, and as definite in its results as that 

 seen in the organic kingdoms. The author 

 next considered the conditions of softening 

 and displacement of indigenous rocks, which 

 permitted them to assume in many cases the 

 relations of exotic rocks, and to become ex- 

 tended after the manner of lavas, as seen in 

 ths case of trachytes and many granite-like 

 rocks. Such masses he designated p.scudo- 

 plutonic. 



Effieiency of Exploslyog. — It is pointed 

 out by Professor Charles E. Munroe, in his 

 "Notes on the Literature of Explosives," 

 that the theoretical efficiency of an explo- 

 sive "can not be realized in useful work 

 for several reasons, viz. : because of incom- 

 plete explosion ; because of the compression 



and chemical changes induced in the sur- 

 rounding mineral ; because of the energy ex- 

 pended in cracking and heating rock which 

 is not displaced ; and because of the es- 

 cape of considerable quantities of the gases 

 through the blast-hole and the fissures made 

 by the explosion. In all probability the ex- 

 tent of these losses can never be determined 

 by direct experiment, as the phenomenon of 

 an explosion does not admit of a close ob- 

 servation ; nor can it be determined by com- 

 parison with the work done under other cir- 

 cumstances, as we arc as yet uncertain as 

 to the so-called dynamic resistance of rock. 

 The useful work of a blasting charge is em- 

 ployed partly in shattering the rock and 

 partly in throwing or displacing the shat- 

 tered masses. It is a familiar engineering 

 problem to reduce the projectile force of a 

 blast to a minimum by means of suitable- 

 sized charges, properly located in blast- 

 holes of estimated dimensions, and so avoid 

 the cannonading of which workmen are 

 fond. With the discovery of at least ap- 

 proximately correct values for the useful 

 work of charges, we are now able to dem- 

 onstrate the correctness of this principle." 



Mistakes in treating Organic Refnsc. — 



Most of the shortcomings of modern sani- 

 tary methods, says Dr. G. V. Poore, are due 

 to the fact that, in our dealing with organic 

 refuse, we commit a scientific error — i. e., 

 we pursue a course that is in opposition to 

 natural law. This error consists in mixing 

 organic refuse with water. It then under- 

 goes changes which differ widely from the 

 changes which it undergoes when mixed 

 with earth. According to WoUny, the pro- 

 cess of oxidation of organic matter and the 

 formation of nitrates take place most readily 

 when a moderate amount of moisture is pres- 

 ent, and the most favorable amount is about 

 thirty-three per cent. When water is in ex- 

 cess, the amount of free oxygen is insufficient 

 to favor the growth of mold-fungi,>the schizo- 

 mycetes (bacteria and micrococci) arc formed, 

 and, in place of oxidation, putrefaction oc- 

 curs, with the formation of ammonia, free 

 nitrogen, carbonic acid, and carbureted hy- 

 drogen. This process of deoxidation takes 

 place in mixtures of putresciblc matter with 

 water, and takes place also, it is said, in soil 

 which is thoroughly soaked in sewage. In 



