_Direct Fire Dryers._--In direct fire dryers, the tankage and flame produced by the use of oil, coke or coal, are introduced and passed through a cylindrical rotating machine similar to a cement dryer. The dried tankage is discharged at the opposite end from the feed, and the gases and moisture pass through a water spray and chimney to the air. It is practically impossible to operate a dryer of this type without producing an offensive odor in the surrounding territory and they are also considered hazardous from a fire standpoint. _Smith Type._--This type of dryer is shown in the illustration (Fig. 75) and is of the steam jacketed type. The barrel is stationary with a revolving shaft and extended arms carrying the tankage upward which falls back through the air. _Ord Type._--This dryer is also illustrated, Fig. 76, and is of the same type, except that the shaft is placed vertical and the revolving arms at right angle to the shaft device which accomplishes the same result. [Illustration: FIG. 75.--ILLUSTRATING THE SMITH TYPE OF DRYER.] [Illustration: FIG. 76.--SHOWING THE ORD TYPE OF DRYER.] =Expense for Drying.=--In a charge type of machine where batches are placed in the machine and unit lots dried, the expense for drying seems to be per short ton, about as follows: Labor, $1.25 to $2.00; Dryer repairs, $0.75 to $1.25; Steam, variable. The item of steam is quite a large factor. In a well handled equipment, properly insulated, about ³⁄₄ of a pound of moisture can be extracted per pound of steam condensed in the jacket, when drying tankage, and ⁶⁄₁₀ of a pound when drying blood. The latter requires about twice as long to dry as tankage; in other words, the output per hour of dryer operation is about one-half. =Commercial Fertilizer.=--Commercial Fertilizer is the name generally applied to prepared or diluted mixtures thought to be best adapted for use on ground or for some special crop. The standard tankage as produced contains an ammonia content of from eight to twelve per cent and may be short in other ingredients such as potash and acid phosphate, which are mineral substances, usually converted to a form readily soluble, or in condition to be assimilated. Also the ammonia content is reduced to a moderation, the dilution being accomplished by the use of a filler, such as pulverized dried peaty soil, which has the advantage of carrying a certain quantity of humus or selected sand which serves a drill nicely. =State Regulations.=--Most states have found it desirable to protect the purchaser by insisting that an analysis of the fertilizer be supplied with each shipment, indicating the content, the state then making sporadic analyses to see that it generally qualifies to the stated contents. =Mixing Materials.=--The mixing materials used are: Dried Tankage. Dried Blood. Bone Meal. Steam Bone.