338 



SCIENCE. 



remarkably like that which is often produced on a small 

 scale in electrical experiments. This brush shone very 

 distinctly against the heavily overcast and darkened 

 sky ; and it looked about as large as the hand of a half- 

 grown child, with the fingers spread moderately apart. 

 After one or two seconds it seemed to change into a ball 

 of fire, of smaller size but greater intensity, and distinctly 

 round in outline, which glided smoothly down the sur- 

 face of the mast and across the wooden deck, until it 

 passed over the stern of the boat and entered the water 

 with an explosion not unlike the report of a large pistol. 

 There was no lightning-rod upon the vessel, but the 

 wood of the mast and of the deck was quite wet by the 

 time the ball passed over it. The electrical disturbance 

 did not approach the mast wiih a visible flash, and the 

 sound of the explosion, the only sound noticed, was de- 

 cidedly from the direction where the ball entered the 

 water. The ball left the mast in a line at right angles 

 to a tangent at the point of departure, while the nearest 

 course to the sea would have been in the direction of the 

 tangent ; but having once commenced to cross the deck 

 it took a perfectly straight course. The wood over which 

 it passed was slightly discolored in several places, but not 

 at all charred. 



On another occasion I was standing, with several com- 

 panions, in a carriage-house, in the country, having taken 

 iefuge there from a sudden shower. Through an open 

 door we were gazing intently upon a large barn near by, 

 discussing the safely of occupying that more commodious 

 retreat, when a flash of lightning, in the usual zigzag 

 form, passed obliquely from the clouds to the barn, strik- 

 ing the ridge at the very summit of the roof. Thence it 

 passed, as a distinct ball of fire, over the wet shingles 

 down the surface of the roof to the eaves and there 

 entered the barn. We thought there was a report as the 

 ball entered the barn, which had been recently filled with 

 freshly gathered hay, but were not certain, owing to the 

 nearly, if not practically, simultaneous arrival of the 

 thunder sound. The nearest door of the barn was opened 

 within a very few seconds, and the interior was found 

 filled with fire and smoke ; although the roof over which 

 the ball had passed remained unaffected until destroyed 

 by fire breaking out from within the building. Although 

 I had been the only one in the party to insist in taking 

 refuge in the carriage-house instead of the barn, there 

 seemed to arise on the part of the majority a considera- 

 ble unwillingness to further dwell upon the reasons for 

 preferring the latter place of safety. 



R. H. Ward, M. D. 



To the Editor of" Science." 



Allow me in reply to R. C. S. again to tell him, most 

 emphatically, that I have never entertained, for a mom- 

 ent, the idea of " reviving " or advocating the theory that 

 motor cells can be distinguished from sensory ones by 

 their size. In order to " revive" a theory it must be re- 

 stated in some form. In the " transactions " of the 

 American Neurological Association, published in the Jour- 

 nal for Nervous and Mental Disease, July, 1880, p. 476, 

 I am correctly reported as stating that " so far as sensa- 

 tion went, it had nothing to do with the subject of the 

 paper." My theory relates exclusively to the nuclie in 

 so-called motor cells. They are called motor not by any 

 means on account of their size, but from their evi- 

 dent connection with motor filaments. In spite of my 

 denial, R. C. S. still asserts the wrong thing, and shows 

 none of the customary regret at having possibly misun- 

 derstood me. 



Prof. Stieda is referred to by me not to " polemize " 

 against him, but to show that, while he had measured 

 their cells and their nuclie in the spinal cord of turtles, 

 he had not anticipated me in attiibuting difference in 

 size to difference in energy. Stieda's expression is ; 



Physiologische Dignitat, which I translate physiological 

 importance. As neither sensation nor sensory cells are 

 here mentioned by him, it seemed plain that he, like my- 

 self, referred solely to cells of the spinal cord which, by 

 their close relation to motor filaments, are supposed to 

 have a motor function. 



The careful reader for whom R. C. S. so dogmatically 

 responds, is respectfully requested to bear in mind that 

 the three brief articles which I have published, relate 

 throughout to Reptiles and Batrachians, and not to mam- 

 mals. With this reminder he will have, I think, no 

 difficulty in reading, in some places, between the lines. 



As to the auditory nerve centres, it remains for me to 

 state that the paragraph which R. C. S. quotes was 

 offered as a mere suggestion to one who seemed also to 

 think that the large cells in the vicinity of the roots of 

 the auditory nerve, in the iguana, bore some relation to 

 my theory. As his communication was stated to be pre- 

 liminary in character, and had nothing to do with my 

 subject, I decided to make no personal reference, sug- 

 gesting that these cells (as claimed fourteen years ago by 

 Deiters) were of doubtful function, and that the cells re- 

 lated to vision and olfaction were (in reptiles, etc.,) all 

 very small. This, I believe, is true, but it revives no 

 theory. 



I leave my unknown critic to the contemplation of this 

 clause which appears in his last publication : " Notwith- 

 standing the construction which Dr. J. J. Mason now de- 

 sires to see placed upon his words," doing him the jus- 

 tice to suppose that he knows what he insinuates, and 

 that being mortal, he will hasten to admit that he may 

 have misunderstood me. 



John J. Mason, M. D. 



Newport, R. I., July 2, 1881. 



Decomposition of Water. — In decomposing water by 

 discharging Leyden jars through platinum electrodes, Dr. 

 Streintz finds that, with very small electrodes giving pass- 

 age to a series of discharge currents in one direction, and 

 then left to themselves, a remarkable reversal of E.M.F. oc- 

 curs, but only when the discharges do not exceed a certain 

 number. Dr. Streintz made use of a quadrant-electrometer 

 in his experiments. 



Simple Method of Determining the Temporary 

 Hardness of Water. — In order to ascertain the alkalinity 

 of springs on the spot, with samples not exceeding 10 c.c, 

 and with a single reagent, the author makes use of a tube 

 of 30 to 40 cm. long, closed at the bottom, and with a mark 

 showing the capacity of 10 c.c. From this mark upwards 

 the tube is graduated into 0.1 c.c. To determine the tem- 

 porary hardness the tube is filled to the lowest mark with 

 the water in question, and a little piece of filter-paper, which 

 has been previously steeped in extract of logwood and 

 dried, is thrown in, thus giving the water a violet color. 

 Centinormal hydrochloric acid is then added from a drop- 

 ping bottle, till the color of the liquid inclines to an orange. 

 The tube is then closed with the thumb and well shaken. 

 The greater part of the carbonic acid escapes, and the liquid 

 becomes red again. Acid is again added, and the shaking 

 repeated until the next drop of the acid turns the liquid to a 

 pure lemon-yellow, a point which a little practice is easily 

 reached. The amount of acid used is read off on the tube 

 itself. The author proposes to express the alkalinity of a 

 water by the number of c.c. of centinormal acid needed to 

 neutralise 10 c.c. He thinks that this method will be found 

 useful both for sanitary and geological purposes. — V. 

 Wartha. 



Chemistry of the Platinum Metals. — Contrary to the 

 prevalent view, all the platinum metals, if precipitated by 

 zinc in a state of very fine division, are soluble to a con- 

 siderable extent in nitric acid, whether weak or strong, 

 so that palladium cannot be separated from such a mixture 

 by means of nitric acid. The solubility appears to depend 

 on the relative proportion of one or other of the metals in the 



