Cu
+ H(NOJ +Cu(N0t)r + NO + Hz0
+
Now let the unknown coefficientsbe a, b, c, and d as we go from left to right. Looking a t the elements and their subscripts we get Equation 1 from capper.. ........... .a Equation 2 from nitrogen.. b Equation 3 from hydrogen.. ......... .b Equation 4 from oxygen ........... .3b -
...........
~
=c = 2c
= 2e = tic
MnO,
d
+d +c
be the It is apparent that it simplest to resolve all values in terms of "a." Thus we have directly that c = a. But b = 2e (Equation 6c - d (Equation 4) and d = 3). Since e = 3b b 2c (Equation 2), we have by substituting e = 3b - 6c - b 2c. But e = 1l2b and c = a. Thus l/zb = 3b - 6a - b 2a or b = 8/aa. Then from Equation 2 we have a/3a= 2a d or d = '/&. Then e = 1/2b (Equation 3) or, since b has been found to have a value of a, then e = %a. So we now have b=8/sa, c =a, d= 2/sa,and e=4/8a. Letting "a" equalunity, we have Cu + a/1HN08 +Cu(NOs)a '/rNO 4- '/tH*O
-
-
+
+
+
+
and clearing fractions: 3Cu 8HNOn --+ ~ C U ( N O ~ )2NO ~
+
+
+
+ + 3d +
2c Equation 1 from hydrogen.. ..........3a = b Equation 2 from phosphorus.. ........a = b 4- d Equation 3 from oxygen.. ...........3a = 36 c
Here i t seems more logical to resolve in terms of d. We "c." It is known that (Equation 2) a = b can then substitute in Equation 3 so that 3b 3d = 3b c. Canceling 3b on each side we have 3d = c or d = '/&. Subtracting Equation 2 from Equation 1 we have. canceling "b" in each equation &at 2a = 2c 2d. But d = c so 2a = 2c or a = J/G NOWsolving for b in Equation 2 we have 'lac = b I/JC orb = C. Now we have a = '/%c, b = c and d = '/ac. Letting "c" equal unity we have
+ +
+
+
+
'/rHPOs
-+HPO
+
+ Hz0 +
or clearing fractions we have 4HnPOa --+ 3HPOa
'18
PHI.
+ 3H10 + PHa
And finally one involving seven different compounds-MnO,
+ ZNaCl+ 2HdO.--t
Ch
+ Na2S0, + &SO,
f 2H20
And there i t is. Althou~hin some cases the method may appear cumbersome, one is surprised to see how quickly one can develop the knack of securing different combinations, and quickly bring order out of the different equations, It is apparent that the more elements which are involved in the reaction, the more easily the problem lends itself to solution. The value . 1s especially apparent in cases where many molecules are involved in the reaction. Anyhow, i t is lots of fun solving them in this manner, and a t times the fun can be put to practical use. GERALD BARTHAUER~ H
w COLLEGE
HI^, OH~O -
Present address: Purdue University, Lafayette, Indiana.
+ 4H80.
A slightly more difficult example might be the treatment of phosphorous acid to produce metaphosphoric acid and phosphine. We have as reactants HsPOi --+ HPOI HnO PHs
+
from Equation 4 we have 2a = e a or e = a. But b = 2e (Equation 3) so b = 2a. Since b = 2a, then d = a (Equation 2). Now we have b = 2a, c = 2a, d = a, e = a, f = a, and g = 2a. Now let "a" equal unity and we have directly
+ NaCl + H&04 --+ C11 + Na&01+
............ .............. ..... .............
MnSO,
+ HrO
Equation 1 from manganese. .a = f b = 2d Equation 2 from chlorine. Enuation 3 from sodium.. ................ b = 2e ~ o u a t i o n4 from the sulfate radical.. c =c f Equation 5 from hydrogen.. .c = g Equation 6 from oxygen.. .............. .2a = g
+
Smce it appears simplest to resolve in terms of "a" we have directly that (Equations 1 and 6) f = a and g = 2a. From Equation 5 we have c = 2a. Then
ANDREW WITTMAN-DISCOVERER OF ZINC To the Edit09 DEARSIR: R. D. Billinger in a recent paper (1)in THISJOURNAL has ably described the early discpvery and subsequent history of z i n in ~ the Lehigh Valley. In this article i t was declared that the true character of the ore was not definitely known until Mr. W. T. Roepper examined it and identified it as calamine. The present writer in a short paper (2) on the same subject made a similar statement.. Richmond E. Myers in a lengtgy article (3) states that Andrew Wittman conducted several experiments in 1845 and managed to obtain a few globules of metal which he could not identify. This seems unlikely. It is diicult to believe that one sufficientlyskilful to obtain a sample of metal from an ore would b e a t a loss as to how to identify the metarif i t was not immediately recognized from its physical properties. In order to settle the matter one way or another the writer has, during the past several years, examined a large portion of the printed material extant on the subject and has come to the conclusion that Andrew Wittman was not only the first person to identify the ore as a zinc ore but was also the first one to obtain some of the metal. A very interesting paragraph which accurately describes the true sequence of events and which sums up the present writer's views in the matter is to be found in the "History of Lehigh Co., Pa.," by Charles R. Roberts, et al. (4). As this information is hidden in what really amounts to a genealogical record one feels
that it should be made more readily available to all interested in the history of the Friedensville zinc deposits. The paragraph in question, which follows, is found on page 938 of Chapter XLIV, "Upper Saucon Township," compiled by Frank B. Heller. "The discovery of zinc a t Friedensville (like many another important discovery) is generally accredited to the one who first made it known rather than to the real discoverer. The following develops the true process of its discovery, and will serve to place the honor where the same is due. On the west side of the road leading from Friedensville to Bethlehem, a t a distance of about one hundred fifty perches1 from the base of the Lehigh mountain, in the middle of a field fertile and productive in every other part, there was a depression resembling in shape a large bowl, about three hundred feet in diameter, and about twelve feet in depth. On this spot, with the exception of a few sickly weeds, no vegetation would grow. This sterility was attributed by many to the presence of mineral substances in the soil deleterious to plant life, but beyond this no one ventured. The place was visited by one of the State geologists, but he made no report of his observations. On the edge of the hollow a number of bowlders, resembling limestone, projected from the surface. These Mr. Ueberroth, the owner of the land, attempted to convert into lime by the usual process, but failed, the whole mass melting together in the kiln. After this the place was made a repository for rubbish and the stones picked from the farm, and so i t remained until 1845, when Mr. Andrew K. Wittman was called as surveyor to trace a line between lands of Mr. Ueberroth and one of his neighbors. While thus engaged his attention was attracted to these bowlders, and he took pieces of them along home to add to a collection of minerals he was then forming. Taking much interest in minerals, and being of an investigating turn, he resolved upon a test of his recently acquired specimen, resorting first to the blowpipe, then to acids, and finally to the crucible. l$y the latter process he succeeded in obtaining about two ounces of metal, which, from his knowledge of metals, he knew to be zinc. On the following day he met Mr. Ueberroth, told him of his discovery, and gave him a portion of the metal. On the afternoon of the same day Ueberroth visited Bethlehem, and stopped a t Leipert's Hotel, where he exhibited his metal to some friends. Among the sojourners a t the hotel a t the time was Professor T. H. Roepper,= who overheard the conversation between Ueberroth and his friends, saw the metal, and lost no time in proceeding to Friedensville and getting a supply of ore, of which he soon succeeded in making brass by mixing it with copper. Roepper then went to Philadelphia, made the discovery known, and has since been accredited with i t by nearly every one who undertook to write about it, while Mr. Wittman, the l A perch is equivalent to one rod (sixteen and one-half feet). 'Should be W. T. Roepper. The same mistake is found in M. S. Henry. '%istory of the Lehigh Valley." Bixler & Corarin. Easton, Pa., 1860.
real discoverer, has hardly been noticed or mentioned by any." LITERATURE CITED
BILLXNGER, R. D., "Early zinc works in the Lehigh Valley," J. CFIEM.EDuc.. 13, 60 (1936).
BLANK,E. W., "The old Friedensville zinc minw," Rocks and Minerals, 6, 26 (1931). MYERS. R. E,, "The story of the zinc industry in the Saucon Valley," ibid., 10, 17, 33, 56 (1935). Three parts. Contains a bihliaeraohv ..-.. " = . of twentv-sir. titles. ROBERTS, C. R.. e l ol., " ~ i s t o r y a fLehigh Co.. Pa.." Vol. 1, Lehigh Publishing Co.. Ltd., Allentown. Pa., 1914.
THE CHEMISTRY TEACHERS CLUB OF NEW YORK-A WORTH-WHILE - ORGANIZATION To the B i t o r This Club was organized by a group of young chemis-
try teachers on March 20, 1902. It has functioned continuously since that time. At present two hundred fifty men and women who teach chemistry in the high schools and colleges of the metropolitan area are enrolled in the Club. The objectives of the founders of this organization were of three types. It was planned to use the Club for professional p w t h of the members, for promoting fellowship among the chemistry teachers of the area, and for influencing the proper authorities toward a recognition of the importance of chemistry as a part of the school curriculum. The results obtained in these threefields of endeavor have surpassed the expectations of the founders to a considerable degree. In promoting professional growth the Club has visited ninety-two chemical manufacturing plants of over fifty different types, seven industrial laboratories, three research institutes, and three science museums. Over seventy-five classroom experiments and demonstrations have been-exhibited before the Club. .Many of these demonstrations may be found in the chemistry textbooks written by members of the Club. Some sixty-odd speakers, including specialists of national repute, have addressed the Club on chemical and pedagogical topics. The yearly schedule of programs usually consists of a social evening, a science luncheon, an evening devoted to technics of teaching, four lectures on chemistry,two or three plant visits and recently an outing or picnic has been added. Those who participate in these activities receive inspiration and information equal or superior to the average "alertness" course. Abstracts of the speeches and plant visits are sent
