6 



Since few plants- operate under the same conditions, and since a 

 number of products may be obtained from the tar and crude turpen- 

 tine, it is difficult to estimate the amount of products obtained from 

 yellow pine. Moreover, the wood itself varies widely in resinous 

 content. Heavy, rich "lightwood" contains the largest quantities 

 of turpentine and other oils, whereas other kinds of " lightwood " 

 may yield but little. Sapwood yields the least. The following table 

 shows as nearly as practicable the ordinary yields per cord of wood 

 obtained in practice by the destructive process : 



Refined turpentine. ; - 7 to 12 gallons. 



Total oils, including tar 50 to 75 gallons. 



Tar 40 to 60 gallons. 



Charcoal 25 to 35 bushels. 



USES OF PRODUCTS. 



The turpentine is used as a second grade, inferior to gum turpentine. 

 There are no recognized grades of destructively distilled turpentine, 

 and the composition of the turpentine from different plants is not 

 uniform. Formerly it was poorly refined; it is now made practically 

 colorless. In the refining, certain heavy oils are obtained, which, 

 when combined with similar heavy oils from the tar, are made into 

 "pine oils," used as disinfectants, paint dryers, wood preservatives, 

 etc. One of the uses for the tar is cable coating. The uses of the 

 acetate of lime, in this case "brown acetate," have already been 

 mentioned. The charcoal is burned at the plant or sold for fuel. 

 The pyroligneous acid in its crude form is occasionally sold, although 

 most of it goes to waste. 



Several causes have led to many failures among plants of this kind. 

 One of these was bad management. Men engaged in the business, 

 without training or a knowledge of the market, expected an immediate 

 demand for the products. Another cause was the use of inferior 

 retorts, which in many cases were made of thin steel and so were 

 quickly burned out. A third was lack of perseverance when difficul- 

 ties arose. 



STEAM DISTILLATION OF YELLOW PINE. 



The plants which distil wood by the steam method are located in 

 the yellow pine belt. In general, the wood is the same as that used 

 for the destructive distillation of yellow pine, but is separated into 

 classes. -Steam plants use the richest wood that can be secured, since 

 turpentine is the only valuable product, although the wood after 

 extraction is used for fuel. The wood is divided into three classes: 

 (1) The rich "light wood," of which several grades are used; (2) 

 stumps, which are also rich in turpentine; and (3) sawmill waste, 

 which includes sawdust, butt cuts, and slabs. All wood must be 

 "hogged" into chips before it is placed in the retorts. 



APPARATUS. 



Both vertical and horizontal retorts are successfully used. But 

 the wood is treated by two different methods, one using superheated 

 steam under low pressure and the other saturated steam under 

 higher pressure. 



[Cir< 114] 



