Celestial phenomena have ever excited in the un lettered mind a wonoering interest; an interest which in the early ages was seasoned with a large anmixture of superstitious dread. Eclipses of the sun and moon, more often than not, were interpreted as prophetic of approaching disaster and brought much unrest to the minds of men. Science has changed all that; and tbese periodic phenomena are now eagerly anticipated, and closely observed, for the astronomical data which they afford. Formerly the chief use to which the total lunar eclipse was put hy the astronomer was the determination of longitude. The moment of total eclipse is the same tor every station on that half of the globe which faces the moon ; and the observation of this time of totality enables us to calculate the difference of longitude bet ween any t wo points of observation. Such com putations h owever lack exactness, owing to the fact that it is difficult to determine tbe precise moment of totality. The varying density of the earth's atmosphel'e causes a varying intensity in the sun's rays that pass through it. There is consequently no sharp, clearly defined edge to the umbra or shadow, and it is difficult to tell exactly when the edge of tbe moon has passed into it. The most important observation is that of the oc-cultation of the stars. or their passage behind tbe moon. At ordinary times the brilliancy of the moon is such that only the brightest stars can be seen as {hey approach it. During eclipse, and owing to the fact that the moon has no atmosphere, stars of very faint power can be observed up to the moment at whIch they pass hehind the planet. In determining the place of t,he moon by this method the occultation of certain stars is observed simultaneously at different observatories, widely separated. This siderial occultation, which, for the reasons above given, is very exact, is used for calculations of longitude, aud to establish the diameter of the moon, its distance from the earth, and its right ascension and declination. A total eclipse affords a special opportunity of making a spect.roscopic examination of the earth's atmosphere. The sun's rays, during eclipse, pass through the atmospheric envelope obliquely on their way to the moon. Their course at this time through the at- mosphere is much longer than when they fall normally to the earth, as they do during the day time. After being reflected from the moon they again pass through the earth's atmosphere before they strike the spectroscope. In this way the earth's spectroscopic lines are obtained of greater distinctness than is pOBsicle in ordinary observations. The total eclipse has been used to determine the amount of heat thrown out by the moon. During eclipse, for obvious reasons, the moon cannot give off reflected heat. Any heat that we then receive must be heat that bas been absorbed from the sun, and is now being radiated. Tbe observations show that as the light fails so does the heat; which proves tbat lunar heat is reflected, not radiated. Many historical dates have been accurately fixed by means of calculations based upon the lunar ecliWe. " The first olvmpiad, the beginning of the Christian era, and the death of Augustus are some of the events wbose dates have been settled by the occurrence of lunar eclipses." The value of the lunar eclipse is discussed in fuller detail in the November issue of Popular Astronomy by Caroline E. Purness, of Vassar College Observatory. The paper closes with an interesting description of the methods of observation adopted by the students of this college during the eclipse of September last. The Electroly.l. oC Milk. Ina somewhat lengthy paper by Mr. C. E. S.Phillips, the author, after referring to some of the tests adopted for ascertaining the purity of milk, proceeds to de- scribe experiments undertaken to discover whether electrolysis would offer a more expeditious and reliable method than those in use. On electrolyzing a sampIe of milk between platinum electrodes, the anode became coated with a white, spongy-looking material which Increased until so thick upon the plate that it ultimately became disengaged and floated to the surface of the milk; it was obser\'ed on making experiments in this way that the white deposit consisted principally of a mixture of caseine and fal, that the milk gave off a characteristic odor during the elec-I trolysis, and it was found to be slightly alkaline after ' the operation. The liberated caseine floating upon the milk seemed to show that, owing to alkalinity of the solution, it had become insoluble ; it was, however, evidently due to the lifting power of the gas bubbles clinging to it. By contmumg the electrolYSIS further It was pOSSIble to extract practically all the solids from the milk used (30 cub. cm.), leaving a transparent solution behind ; at the same time no appreciable deposit of any kind took place at tbe negath'e electrode. Tests made with litmus paper during electrolysis showed that the action was extremely local; it was, however, noticed that the froth on the negative electrode produced by a too rapid electrolysis was strongly alkaline The formation of caseine on the positive electrode was then studied in a miniature cell under the microscope. On making the circuit, hubbies of eas appeared upon each electrode, more of course at the negative one, but at the anode a yellowish deposit grew and spread uniformly out toward the opposite electrode, a dark ridge was built up about equidist,ant all along the electrode, and became more definite till the band widened out on either side. and concentrated at a point immediately opposite the cathode. Very pe-culiar movements could be made to take place in this band by making and breaking the circuit rapidly. Photographs showing these changes are given by the author. A drop of litmus used to stain the milk showed that an acid and an alkali were formed at the anode and cathode respectively. evidently accounting for the deposition of caseine at the former. Tbe action would appear to be similar to that wbich takes place when milk is exposed to air for some days ; lactic acid is formed, wbich throws down the easeine. By electrolysis, however, the action can be started and stopped as desired, so that any portion or all of the 3aseinecanbe removed from the milk. Next a small vessel was divided into three cornpartments by means of two porous partitions, and the jffects recently described by M. Andreoli were tried. About 10 cub. cm. of milk were poured into the center di vision. while the anode and cathode compartments contained a solution of sodium chloride. On the passage of the current a deposit was formed in the center compartment on the side of the partition separating it from the anode. When all three compartments contained milk, the deposit occurred on the sides of both partitions furthest from the anode. Under these cir-cUlIIstan('es it seemsthat an action takes place in the milk in t.he center compartment. No deposit took place upon metallic plates immersed in the milk in either case. Some experiments upon the preservation of milk by means of this olectrical withdrawal of a portion of its caseine were made, but with no success so far. Mr. Swinburne mentions, however, that milk can be sterilized electrol ytically. In conclusion, the author states that platinum is the most suitable material to use for electrodes in the electrolysis of milk, as the lactic acid formed attacks most other metals. Aluminum can, however, be used in certain cases for the positive electrode, but it is eventually dissolved, and cousequently of little use for quantitative work.The Electrician. Field Experiments with Potatoes made by the N"w Jersey Agricultural Oollege are, briefly, as follows : The results of recent field experiments with Irish and sweet potatoes are at least Eug gestive. Manure increases .th.e scab and sOil. rot. Lime increases the scab, but diminishes the soli rot and tends to make sweet potatoes round. Kainit diminishes the scab, but increases the soil rot. Sulphate of copper diminishes both scab and soil rot. Corrosive sublimate diminishes greatly the scab and soil rot. SuI phur is. all things considered, the best remedy for the scab a.nd soil rot that the experiments suggest. For the Irish potatoes. it is suggested that the flowers of sulphur, costing t,wo or three cents a pouud. be used with the freshly cut seed in the hopper of the planting machine. For sweet potatoes the sulphur 'night be mixed with five times its bulk of fine earth, md a spoonful of the mixture placed in the hill just before betting out the plant.