T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
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Vol. 6, N o . 5
TABLE V Variety of wood used in the distillation
Vol. of Per cent pyroligneous wood acid alcohol in in liters pyro. acid
Sugar pine . . . . . . . . . . Yellow pine . . . . . . . . . Stump wood-pine.. . . Red fir . . . . . . . . . . . . . Silver fir . . . . . . . . . . . Millstates.. . . . . . . . . Sage b r u s h . . . . . . . . . .
9.8 12.4 10.9 11.1 10.1 9.6 9.4
0.52 0.55 0.57 0.48 0.51 0.61 3.54
Per cent acetic acid in pyro. acid
Vol. of tar in liters
2.6 2.2 2.4 1.8 2.1 2.7 11.53
1.26 2.09 3.50 1.78 1.23 1.81 1.94
wood turpentine, distilling below 1 7 0 ~ . The results obtained from Experiments 3 a n d 4 are given in Table 11. Sample A is almost colorless and easily purified by distillation, b u t Sample B contains impurities, which can be removed only by alternately washing with caustic soda a n d sulfuric acid a n d redistilling. Experiments 3 a n d 4 were repeated, using samples of other kinds of wood with results given in Table 111. From t h e above results it is evident t h a t t h e yield of turpentine under diminished pressure is from I O t o 20 per cent higher t h a n t h a t obtained a t ordinary pressure, using t h e same method of heat control, while i t is double t h a t obtained by t h e common destructive distillation method. I n addition t o this t h e quality of t h e product is much improved. If, however, as shown b y a number of experiments in this laboratory, t h e wood used is green, a n d contains water in large excess of t h e volume of turpentine, t h e n t h e process becomes one of steam distillation a n d t h e diminished pressure, while bringing t h e distillate over a t a lower temperature, produces no decided increase in t h e total yield of turpentine. I T h e samples of purified wood turpentine, obtained from each of these varieties of wood, is water white a n d looks like ordinary spirits of turpentine, b u t t h e y differ from i t , a n d from each other, in odor and optical properties. They are under examination in this laboratory in a n effort t o identify t h e various terpenes present. When t h e temperature of t h e retort reaches 2 j o o , t h e volume of t h e gases given off is so great t h a t t h e pump is no longer efficient in reducing t h e pressure, a n d distillation under diminished pressure becomes impossible. I n order, however, t o determine t h e total amount and t h e properties of the different products obtained a t various temperatures from western yellow pine, 2 2 kilos of a sample of dry “light wood” were submitted t o distillation in an oil-jacketed retort with results tabulated in Table IV. After t h e distillation there remained 7 . 8 kilos of charcoal. The time for t h e distillation of each fraction was one and a half hours a n d t h e temperature was raised a t almost uniform rate. There are many varieties of wood indigenous t o t h e Pacific coast, concerning the distillation products of which there is no published d a t a . Samples of a number of these varieties, as they occur in t h e lumber districts of t h e Sierra Nevada h/Iountains, were submitted t o destructive distillation. The results obtained are set down in Table V. The amount of wood used in each experiment was z j kilos, and the methods
i
Per cent turpentine oil in tar
Per cent creosote oil in tar
Per cent mixed heavy oil in tar
Per cent pitch in tar
Per cent water in tar
Kilos of charcoal
8.5 10.6 18.1 16.1 11.2 9.2
9.0 6.2 9.0 7.8 11.0 8.1 16.2
15 7 20.2 20.4 18.4 18.4 20.7 14.7
56.1 46.9 50.4 47.1 53.1 48.8 15.6
10.2 6.5 2.4 11.2 8.4 11.8 48.0
3.64 4.32 4.09 5.03 4.77 4.53 7.8
...
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used in t h e examination of t h e distillate are those described in Allen’s “Commercial Organic Analysis.” SUMMARY
T h e above experiments show t h a t : I. T h e western conifers contain wood turpentine in commercial quantities. 11. Under favorable conditions a cord (4,000 lbs.) of yellow pine will yield 2 5 gallons of wood turpentine. 111. T h e yield of turpentine from a given sample of dry wood can be increased b y distilling under diminished pressure. CHEMICAL LABORATORY UNIVERSITY OF N E V A D A
REXO
THE NATURE OF BASIC LEAD CARBONATE B y EDWINEUSTON Received February 24, 1914
I n a n article’ “ O n t h e Composition of White Lead,” reasons were presented for t h e assertion t h a t white lead consists of a mixture of normal lead carbonate with a basic carbonate of lead of t h e composition PbC03.Pb(OH)*. The purpose of t h e present paper is t o consider t h e nature of t h e combination of t h e components of this basic carbonate of lead. The existing assumption in text books on pigments is t h a t , in basic carbonate of lead, t h e lead carbonate a n d t h e lead hydroxide are firmly united in actual chemical combination, b u t t h e results obtained in t h e experiments here t o be mentioned indicate rather t h a t t h e basic carbonate of ‘lead should be considered as among those substances described b y Zsigmondy* as mixtures of colloidal substances which can, under certain conditions, act a s chemical compounds. (‘Not only3 have colloid compounds or colloidal mixtures, in which two colloids are united, been erroneously described as chemical compounds, b u t so also have mixtures or adsorption compounds of crystalloids with colloids.” The fact t h a t t h e lead hydroxide portion of basic lead carbonate is soluble in ammonium chloride solution b u t not in cane sugar solution, indicates t h a t t h e lead hydroxide is not present in mere mechanical mixture a n d yet is not so firmly held a s t o be properly considered in chemical combination. Direct evidence t h a t t h e basic carbonate of lead is a n “adsorption compound” is afforded by t h e fact t h a t , in more t h a n fifty trials, various samples of white lead a n d of lead carbonate, when treated with basic lead acetate solution a t room temperature b y stirring or agitation, invariably withdrew lead hydroxide from t h e solution a n d correspond1 2 3
THISJOURNAL, March, 1914. “Colloids and the Ultramicroscope,” X. Y., 1909, p. 68. I b i d . , p . 69.
N a y . 1914
T H E JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
ingly gained in weight. I n composition t h e samples before t r e a t m e n t ranged from 1 2 . 0 t o 16.3 per cent CO?, a n d after t r e a t m e n t contained as low as 10.1 a n d 10.3 per cent C O ? in extreme cases. T h e extent of t h e reaction under uniform temperature conditions is dependent on t h e basicity of t h e lead acetate solution, on t h e relative amounts of t h e sample t o be treated a n d of t h e available lead hydroxide in t h e solution, a n d on t h e duration of t h e t r e a t m e n t . Merely enough agitation is required t o ensure uniform t r e a t m e n t . T h e process proceeds slowly, requiring, for example, six hours in one instance t o enable a sample containing 14.7 per cent COZ t o join with enough lead hydroxide from t h e solution t o reduce t o 10.1 per cent COS in t h e final product. Excess of basic lead acetate in solution beyond t h e calculated a m o u n t is required for complete action, as t h e end point of t h e reaction is a n equilibrium determined b y t h e relative basicity of t h e solution a n d of t h e sample under treatment. With a sample containing both normal lead carbonate a n d basic lead carbonate this equilibrium can be disturbed in either direction a t will b y t h e addition of a further q u a n t i t y of basic lead acetate solution or b y t h e addition of neutral lead acetate solution. Samples prepared from lead carbonate i n t h e manner described respond t o t h e tests for basic lead carbonate t o t h e extent t h a t their analyses indicate. T o learn whether normal lead carbonate is unique in i t s ability t o withdraw lead hydroxide from basic lead acetate solution, similar trials, using considerable excess of basic lead acetate solution, were t h e n made with kaolin, commercial zinc oxide, basic zinc carbonate, whiting, precipitated calcium carbonate, precipitated barium sulfate a n d precipitated barium carbonate. T h e kaolin gained 10.6 per cent in weight by addition of lead hydroxide, a n d t w o different brands of zinc oxide gained only 0.6 per cent each. T h e other substances named formed compounds corresponding approximately t o t h e following formulae: Basic zinc carbonate became ZnC03.Zn(OH)z.3 P b (OH)?. Whiting became z C a C 0 3 . P b(0H)n. Precipitated C a C 0 3 became aCaCOa.Pb(OH)z. Precipitated B a S 0 4 became 3BaS04.Pb(OH)?. Precipitated B a C 0 3 became 3 BaC 0 3 . 2 P b (0H)2. T h e calcium compounds a n d t h e barium sulfate compound were so lacking in opacity as t o be worthless a s pigments. T h e barium carbonate compound a n d t h e basic zinc carbonate compound showed marked improvement in density, in opacity, in brushing quality, a n d in rapidity of drying with linseed oil, in these respects closely resembling white lead. I n tinting a n d spreading power t h e basic zinc carbonate compound equalled white lead, a n d t h e barium carbonate compound considerably exceeded i t . These results show t h a t other substances t h a n normal lead carbonate form compounds with lead hydroxide from basic lead acet a t e solution, a n d t h a t t h e lead hydroxide so combined tends t o give t o such compounds, in varying degree, characteristics as pigments heretofore ascribed only t o white lead. Further similarity is shown b y t h e lead hydroxide portion of t h e compounds being soluble in
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ammonium chloride solution b u t not in cane sugar solution. T h e slow withdrawal of lead hydroxide from basic lead acetate solution b y normal lead carbonate t o form basic lead carbonate, t h e like action of some other substances in forming lead hydroxide compounds, t h e similarity in some properties conferred b y t h e lead hydroxide on these different compounds. a n d t h e fact t h a t t h e lead hydroxide is present neither in mechanical mixture nor in true chemical combination, indicate t h a t basic lead carbonate is a n adsorption compound. E U s T o N WHITE
LEAD C O M P A S Y ,
ST
1,OUlS
THERMAL REACTIONS IN CARBURETING WATER GAS PART I-THEORETICAL B y hl C WIEIITAKER A S D W F
RITTM4PI’
Received April 13, 1914
Much careful scientific work has been done on t h e equilibria involved in t h e manufacture of uncarbureted blue water gas. I n t h e combined processes of manufacturing and carbureting blue water gas according t o present practice, few experiments have been made on t h e equilibria of t h e constituents t o find out t h e effect of varying pressure, temperature a n d concentration conditions. I n t h e technical literature of gas manufacture, one rarely finds a reference t o t h e relationship which may exist between t h e spheres of reaction in t h e process. T h e natural conclusion h a s been t h a t t h e water gas a n d oil gas reactions are separ a t e a n d influence each other b u t little. I t is proposed t o consider some of t h e factors in which t h e H2, CO, C02 a n d H20 of t h e blue water gas may affect t h e proportions of CH4, CzHs, C?H4, Hf, etc., resulting from t h e cracking of t h e gas oil which is added. Likewise t h e influence of t h e gases coming from t h e oil on t h e percentage composition of t h e final gas mixture will be considered. When t h e blue water gas or oil gas are manufact u r e d in separate operations, hydrogen is t h e only gas which is found in t h e free state, in a n y quantity. B u t if t h e two gases, separately made, should be brought together a t high temperature in a container such as a gas plant superheater, would there not be new equilibria t o be satisfied? For example, might not t h e C O a n d H? of one become CH1 a n d H2O of t h e other, or vice versa? I n case of these new equilibria there would, of course, be vital reactions between t h e gases of t h e t w o processes. I n actual manufacturing practice, all t h e gases produced are in intimate contact a t high temperature for t h e greater p a r t of t h e manufacturing period, i. e., ayhile passing through t h e carbureter a n d superheater. Is i t t h e n correct t o regard carbureted water gas as t h e result of t w o distinct reactions? Equilibrium conditions t e n d t o establish themselves both during t h e periods of initial cracking of t h e oil a n d t h e subsequent passage of t h e mixture through t h e carbureter a n d superheater. Gas oil itself can be “cracked” in a short distance, as has been shown in practically all laboratory experiments; in t h e laboratory t h e length of t h e cracking t u b e is usually a question of inches. I t would seem on a p r i o r i grounds t h a t t h e only important reason for t h e existence of t h e superheater is t o enable t h e various
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