Vol. XIV. No. 349. 



THE AGRICULTURAL NEWS. 



29: 



preserving the dried material until it is' needed foi extraction. 



The equipment ries for the direct manufacture 



of white si lie i m which is 



much discu Itecenl ad u in the 



i 



ture very fine grades n the juice 



of tl The prod . 



which can be stored foi I ol tinu without loss, 



oilers i n il detcrior 



ation, and thus enabh s the [j 



the most favourable tinu ol elling. In connexion with 

 white sugar, the problei unification are exceedinghj 



important. Among the new clarifying substances which are 

 studied should be mentioned various hyposulphite 

 preparations and infusorial earth. JCew'decolourising agents 

 of high carbon contei is Norit and Eponite are also 



being investigated both as to their use in refining and in 

 making white sugar upon the plantation. Recenl experi 

 merits show these new charcoals to be vastlj superior to 

 bone black in decolourising power. 



New uses are being discovered each year for the employ- 

 ment of sugar in the arts. The utilization of the waste 

 sucrose in sugar factory residuums presents each year some 

 new unexpected feature. The employment of molasses for 

 the production of industrial alcohol, for the manufacture of 

 mixed eattle foods, and for many other purposes has so 

 increased that the subject ol molasses is forming a very 

 specialized branch of sugar chemistry. Mention is made by 

 1 >r. Browne of the recent use made of morose in Germany 

 for the growth of yeast which can then be used as cattle 

 food. Reference to this subject has already been made in 

 the Agricultural News in some detail, but it has not been 

 mentioned that a feature of the process is that the urine 

 of cattle can be used as a source of nitrogen for the yeast. 

 In the nitrogen cycle urea-protein in the yeast and protein- 

 urea in the animal is thus an endless one. 



Turning to efforts that have been made to synthesize 

 cane sugar, Dr. Browne gives an interesting historical account 

 of the work that has recently been accomplished. The goal 

 aimed at has however not yet been gained, yet the 

 synthesizatiou of sucrose is a poblem worthy of the best efforts, 

 and its accomplishment will rank as one of the greatest 

 triumphs of organic chemistry. 



Lastly, attention is given to the improvement of methods 

 for estimating sucrose. The polarization of sugar products is 

 performed at present very much as in the day of Soleil 

 seventy years ago. Yet this most simple of analytical 

 operations presents a large number of problems which still 

 await solution, as for example the volume of precipitate error 

 in clarification. Finally mention is made of Clerget's method, 

 which is described as the most beautiful perhaps of the many 

 contributions of French genius to sugar analysis. It is 

 stated that this method in principle is ideally perfect, but from 

 a practical point of view it is still being investigated, and the 

 question.- involved are so complicated that the subject may 

 always be expected to come up for discussion. 



The cultivation of seaweed as a source of manurial 

 potash is described in a note in the Bulletin of the Imperial 

 Institute for April-June 1915. This is being carried on in 

 certain parts of Ireland. The price per ton of the weed in 

 1913 was about l"is to His. but at the present time owing to 

 the enforced demand for potash higher prices are being 

 obtained. The cultivation of seaweed has also received 

 considerable attention in the United States, particularly on 

 the Pacific Coast. 



A NEW SACCHARIMETER. 



One of the many optical instruments which the English 

 opticians have allowed the Germans to supply almost 



ly is the saccharimi i Thi insti iment used to be 

 made by Browning, but in tate years nearly every 

 purchased in England lia come from Berlin from the firm 

 of Schmidt and Haensch, who make several di 

 and small instruments. It is therefon are to find 



an English firm Messrs. Bellingham and Stanley, ol 

 London making a which introduces valuable 



improvements on the German design. The one to which 

 we refer is of the half-shadow type with quartz compensating 

 wedges, but instead of the usual long wi d-r of which the 



movement is read direct by a scale arid vernier, this one lias 

 a short Wedge of lai ;lc. The wedge is moved by 



a screw, and the movement is read on a large drum wi 

 open scale and sliding pointer. The whole length of the 



scale is some 2 feel in ti id of 1 .'. or 2 inches, and it can 

 thus be read with great ea 



In instruments making use of a quartz wedge of the 

 usual length (about ■"> cm.), the scale is nearly always uneven, 

 and unless calibrated, introduces errors amounting to several 

 tenths of a degree Ventzke. According to Landolt this is 

 due to the quartz, which he describes as 'a poor material 

 optically:' he says that one seldom finds faultless plates, and 

 that a pure wedge 3 cm. long is rare. Hence the value of 

 the short wedge of Bellingham and .Stanley which is less 

 than half the usual length. The advantage of such a wedge, 

 even if the quartz is not of special quality, is greater than 

 would appear at first sight, since the field is due to the 

 average effect of the whole of the light passed through the 

 wedge, and this average will vary evenly through the small 

 change of area of the wedge due to its movement, and thus the 

 scale will be regular in spite of variations in the quartz; also 

 it is easier to get repeated readings, owing to the greater ease 

 with which the setting can be made with the fine adjustment 

 given by the series, as compared with the usual rack and 

 pinion motion. In fact, the makers state that they have not 

 detected any calibration errors in their instruments. Another 

 valuable feature is the enclosure of the scale and all working 

 parts, so that they are protected from the salt vapours. The 

 importance of this needs no emphasis to those who have had 

 experience with instruments of this character. The corrosion 

 of the metal work — especially steel work — and of the scale, 

 when as in the higher priced instruments this is engraved on 

 silver or nikelin, under the action of the fumes in a laboratory 

 often renders the instrument almost unusable in a few years. 

 The instrument is mostly constructed of an aluminium alloy, 

 protected by a black-stoved enamel, and no steel is used 

 except for a small spring, which is entirely enclosed. 



The optical work is of the first quality. The dividing 

 line is sharp and clean, and the field evenly illuminated, so 

 that adjustment for equality can be made without ambiguity, 

 and with corresponding accuracy. The makers calibrate the 

 scale at a number of points by direct reading against a pola- 

 rise! rotated on a divided circle. Tn the instrument examined 

 the divisions were in half degrees 'Ventzke' (of which 100 

 correspond to 34"68" of arc, for sodium light at 17'5'C), and 

 it was easy to estimate to tenths of a degree, i.e., to less than 

 three minutes of arc. The design and workmanship were all 

 that could be desired. The same firm is also making refracto- 

 tneters of the Abbe ami Pulfrich type and other optical 

 instruments. (Nature, July 29, 1915.) 



