to draw the required nourishment from the soil. This nourishment, therefore, must be obtained from the cane, and glucose, found abundantly at the nodes, is this food. As the glucose near the node is used up, sucrose in the adjacent cells breaks down into glucose, the form in which it can be assimilated by the bud. Analysis shows that when the cane is growng the percentage of glucose present is high. When the cool nights of October arrive, the plant stops growing and the glucose, which is a sugar which will not crystallize, is converted in the plant into sucrose or the crystallizable sugar we use. The mother cane then contains two plant foods, glucose and sucrose, the former for immediate, the latter for future use. The chemist who discovers a method of converting glucose into sucrose will make an enormous fortune. As nature does it, the prob

lem is seemingly possible of solution.

In its growth the sugar cane takes or converts that which it takes into many different products. Thus it absorbs silica and more or less bitter salts from the soil. It forms many nitrogeneous compounds or mucilages and gums. In the manufacture of sugar from the cane it is essential or desirable to get rid of undesirable compounds from the syrups from which the sugar is crystallized or from the molasses after the sugar has been removed. In the manufacture of sugar the value of the molasses formed is no inconsiderable asset. Molasses that can be utilized for table use is far more valuable than molasses fit for feeding cattle or from which to make alcohol. New ground, rich in salts that are bitter to the taste, may make a good sugar crop, but the resulting molasses may be so bitter from the contained salts that its use for the table is impossible. On the other hand, old land or land which has been cultivated for years may produce excellent table molasses, although the sugar con tent of the cane may be low.

The sugar juices in cane are contained in cells much as the juice is contained in oranges. To obtain the juice the cane is crushed in a two-roller mill with specially formed rolls. About 35% of the total normal juice is obtained from this first mill. Further this is the best juice, as it is freer of impurities. This first mill prepares a mat of crushed cane to be passed on to three roller mills. Experience shows that a larger percentage

of juice can be obtained by repeated crushing and wetting with more or less hot water the crushed cane before it comes to a mill. The crushed cane coming from the last mill will contain about 50% thin juice. Evidently the more nearly this thin juice. resembles water the less sugar it will contain. Hence the addition of water just before final crushing is justified.

Conditions of cane sugar manufacture vary greatly. Thus in Cuba or tropical countries the cane is allowed to mature, the sucrose or sugar content is high and the crushed cane or bagasse makes excellent fuel. The season for cane cutting and sugar making lasts six months. In Louisiana the cane is not allowed to mature. If standing cane is frozen and subsequently thawed the cane splits, thus exposing the juices to the bacteria of the air. The juice then sours, its sugar content is readily reduced and much trouble arises in boiling the juices. In boiling down to syrup the juices will foam or make bubbles similar to that seen in a kettle when it boils over. Afterward when the syrups are being boiled in the vacuum pan there will be a gummy mass to handle and crystallization will be slowed down. Hence in this State planters must start early enough to let them finish cutting all cane before the time when heavy freezes are expected. When grinding is first started there is little sucrose in the cane and the sugar produced per ton of cane is low. The molasses content is high. As the colder weather approaches the sucrose content of the cane increases, the glucose content decreases. The season lasts from two to three months, and the bagasse or fuel for the boilers comes from unripe or green cane.

The short season and the uncertainties of tariff legislation deter the planter from investing in the expensive and complicated machinery necessary for the highest economy in sugar production. Many of the local plants have gradually grown in size and so are not systematically arranged and contain much apparatus now out of date.

The conditions in Cuba allow the investment necessary to erect a first class plant. The modern Cuban house is electric driven throughout, even the mills are motor-driven. The electricity is obtained from generators driven by steam turbines of high steam economy. This results in a large economy as the evaporation is done in quadruple or quintuple effects which are

operated in an economical manner. In the extraction of juice there is also a considerable economy through the use of at least five three-roller mills following a crusher. It will be noticed that these economies fit into one another.

In Louisiana only double or at the most triple effects are used. These require far more steam than the Cuban effects and hence it is useless to employ a highly economical engine or steam motor as there must be enough steam to operate the effects. In many cases live steam from the boiler is admitted to the first effect, although this is far from an economical use of the steam involved. Similarly the cane is crushed in a crusher and two three-roller mills. Cuba then has many advantages over this State, but on the other hand it has also disadvantages. In the recent revolution in Cuba many plantations lost their entire cane crop through incendiary fires, and in addition had to contribute in other ways to the rebels.

The changes experienced by the juice are quite approximately shown by the following illustration. Assume ten cubic feet of juice that has been properly clarified or freed from gums and mucilages and decolorized as much as possible. In the multiple effect these ten cubic feet would be reduced to two cubic feet by the evaporation of water. This unit of two cubic feet LOW contains all the solid matter in the original ten cubic feet, . and is now called syrup and looks much like table syrup. In the vacuum pan by further evaporation of water a reduction in volume of 50% occurs, and we now have a mass of one cubic foot of what is called masse-cuite (cooked mass) composed of 50% sugar crystals and 50% molasses. The actual volumes handled are large, an ordinary vacuum pan is 9 feet in diameter and 12 feet or more high. From the pan the masse-cuite is dropped into a mixer, whence it is distributed to centrifugal machines. In these by the action of centrifugal force the molasses is separated from the sugar crystals. We thus obtain the first sugar and first molasses. In crystallizing all impurities are left behind, and so the molasses contains all the dirt, sulphur, lime, glucose and gums that were in the juice when sent to the multiple effect.

The first molasses still contains crystallizable sugar that may be extracted. The first molasses after treatment may be re

boiled in a second vacuum pan and a second masse-cuite obtained. The sugar separated from this is second sugar and the molasses a second molasses. The operation may be repeated a third time, but crystallization is now so slow that the massecuite is put in wagons and kept for a year in a hot room to give the sugar time to crystallize out.

Pure sugar is perfectly white. Any color that a sugar crystal may have is due to the mother liquor caught between small particles in the process of crystallization. The darker or dirtier the mother liquor or molasses the darker the sugar. The sugar crystal is a flat rectangular parallelopipedon with neatly beveled edges. A piece of flooring board a little longer than it is wide with beveled edges might represent an enlarged crystal.

An ordinary house grinds 1,000 tons of cane per day. In Cuba there are houses grinding 7,500 tons per day. As stated a moment ago water is sprayed on the cane during crushing, and although the juice extracted is about 80% of the cane weight. the weight of the juice is frequently 10 or more per cent heavier than the cane crushed.

As the volume of the juice must be reduced about 90% by evaporating water from it, it is evident that there must be some economical form of evaporating apparatus used.

In each sugar house there are two different apparatus used for evaporating the water from the juice. In one, economy of evaporation is the prime essential; in the other, after boiling, there is a viscous tenacious mass that must be discharged as rapidly as possible, and efficiency in this direction is an essential element. In the multiple effect the original juice is reduced about 80%, and in the next vessel or vacuum pan there is a reduction of 10% of the original volume or about 50% of the volume of the syrup received from the effect.

In the evaporation of cane sugar juices the temperature of those juices should not exceed 234° Fahrenheit for fear of discoloring the sugar that is to be made. An effect is simply a heater or a condenser, depending upon the point of view. Exhaust steam from the engine admitted among a lot of tubes in the effect evaporates water from juice on the other side of the tube heating surface. In a single effect the steam arising from the juice passes into a condenser carrying a vacuum. The fall

of temperature is that due to the difference of the temperatures of the exhaust steam and that rising from the juice. In a double effect the pressure and the temperature on the juice side of the first effect would be higher than in a single effect, and the steam arising from the juice would be used to evaporate water from juice in a second vessel.

In modern houses the amount of heating surface in the first and second effects is far greater than in the third and fourth effects. Then the first and second effect are robbed. That is all the steam arising from any effect is not sent to the next effect, as a part is diverted to some juice heater or even to a low pressure pan. In Germany not only are effects robbed in this manner but preheaters or Paulys are used.

MR. MURPHY-In speaking of filters I understand that the author intended to filter the scum only, not the juice.

A MEMBER-I would like to ask if the use of electricity would not apply here, as well as in Cuba.

PROFESSOR CREIGHTON-The reason it is not used is this: In Louisiana, with the double effect, all the steam that the engines exhaust is used in the first effect and very frequently live steam from the boilers is also needed. The effects need so much steam; there is no way of economizing. The conditions in Cuba are very different. Using a crude engine a quintuple effect would not need all of its steam. You put in an economical engine to avoid blowing off steam all the time. The house is run on bagasse alone. You have to take into consideration the entire house, not a part only.

MR. BURWELL-But for a new house being designed?

PROFESSOR CREIGHTON-Would it be economical to put in quadruple or quintuple effects in Louisiana with a sixty-day season? That is the question.

MR. BURWELL-What about practicing economy in the boilers?

PROFESSOR CREIGHTON-There was very little experimentation on burning bagasse until Mr. Kerr took it up. In Mr. Kerr's experiments, where he simply made experiments on a