106 



NORTHERN SUGAR INDUSTRY. 



a more simple and a cheaper instrument should be devised for general use. 



Mr. Trannin, a French sugar chemist, has attempted this, and has in- 

 vented an apparatus which in simplicity leaves nothing to be desired. 



Fig. 13 shows this instrument. (2) Fig. 13 shows the appearance of 

 the field of vision when the tube [t], which holds the sugar solution, is 

 empt}^ or not adjusted. (1) Fig. 13 represents the same when the sugar 

 solution is in the tube, and the adjustment made, ready for reading. 

 No particular skill is required in the use of this instrument, audi have 

 found that successive readings do not dilfer by more than one-half of 

 one per cent. 



It promises therefore to be of great use to manufacturers. 

 I append Mr. Traunin's description of his invention. 



SACCHARIMETRE DES RAPERIES.* 



Impressed for a long time with the incoraple.e and often deceitful ideas which the 

 use of the densimeter alone giVes, I have sought whether it might not he possible to 

 devise a more rapid method of analysis of the juice (optically) and one more accessible 

 to employes little skilled in polarimetry. 



The large saccharimeters aside from their very high price, are really very difficult 

 to manipulate. The large number of pieces of which they are composed, their ar- 

 rangement, and extreme delicacy of adjustment, create many causes of error. 



These instruments are touched with a sort of fear, and they are committed only to 

 careful and skillful operators. 



The problem of light for the saccharimeter is often a cause of ennui and difficulty. 

 Now it is the monochromatic light which is required by the instrument, and with it, 

 its mode of xjroduction so troublesome. Again it is the delicate appreciation of the 

 shadows, or the chromatic equalization impossible to be obtained by eyes affected 

 with daltonism. These difficulties are real, and indeed some mauufacturers have been 

 compelled to discontinue the use of the saccharimeters, not because these instruments 

 were poor, but because their continual use was not practicable. 



It was to avoid these inconveniences that I ai)plied myself when I invented the 

 little Saccharim^tre des raperies. " Have I succeeded? Practical experience, on 

 which I rely in all confidence, will answer. 



First of all, I wished to do away with every kind of compensator, analyzing circle, 

 and other movable optical pieces. The apparatus is thus reduced to three funda- 

 mental pieces, viz, the polarizer, the polariscope and the analyzer. These pieces are 

 all fixed and therefore cannot be put out of order. 



The light used may be either daylight or a gas or oil lamp. I have noticed, however, 

 that the sensibility is greater witti artificial than with daylight. The appreciation of 

 the critical phenomenon, i. e.,of the phenomenon which is to be obtained when the read- 

 ing is made, is particularly easy. 



Two black bands are on the field of vision. These are to be brought exactly end to 

 end and the reading is then made. 



This phenomenon is so easy of observation that persons the least accustomed to 

 making readings do not show the least hesitation in reproducing them. 



Finally each one uses his usual means of vision. He who has normal sight does 

 not need any aid. As to myopes and presbytes (long and short sight) they retain the 

 glasses to which they are accustomed. The apparatus is therefore always ready for 

 everybody. 



The reading is made directly on a scale graduated into hundredths and half hun- 

 dredths of sugar. 



The apparatus is nickel-plated and consequently always clean and bright. t 



*Sucrerie indigene, vol. xxii, p. 329. 



+ Apparatus furnished by Queen & Co., Phiadelphia. 



