334 F. A. Gooch and P. E. Browning — Determination 



formation and tuning deprived of all its upper harmonies. 

 This method is to be preferred when we wish to obtain a sim- 

 ple harmonic current of definite frequency to drive a synchro- 

 nous alternating current motor, that is to say, a simple harmonic 

 current, carrying with it a large quantity of power. I hope that 

 I shall be pardoned for observing here that this last method was 

 worked out by me some time ago. But in conversation with 

 Mr. Nikola Tesla this distinguished experimentalist informed 

 me that he obtained a patent about a year ago on the method 

 of generating alternating currents of any frequency by means 

 of disruptive discharges. The discovery that I was anticipated 

 in a pretty invention caused me some disappointment at first, 

 but I consoled myself very soon with the idea that a method 

 patented by so excellent an experimentalist as Mr. Tesla, 

 would enable me to obtain the object for which I invented it, 

 the object being to construct a synchronous alternating cur- 

 rent motor which would spin around with great hut perfectly 

 constant angular velocity ■, the angular velocity to he just as 

 adjustable and just as accurately determinable as the time of 

 vibration of my vibrator, the motor to perform the function 

 of a microphonograph. I expect to be able to offer a favora- 

 ble report on this matter very soon. 



A communication of the results of some of my experiments 

 with the simple harmonic currents obtained by the method de- 

 scribed in this paper will be given as soon as time will permit. 



Electrical Engineering Laboratory, 



School of Mines, Columbia College, March 8th, 1893. 



Aet. XXXIX. — On the Determination of Iodine in Haloid 

 Salts by the Action of Arsenic Acid', by F. A. Gooch and 

 P. E. Browning. 



[Contributions from the Kent Chemical Laboratory of Yale College — XXI.] 



Three years ago we demonstrated* the possibility of deter- 

 mining iodine in mixtures of alkaline chlorides, bromides, and 

 iodides, with rapidity and exactness, by taking advantage of 

 the behavior of arsenic acid toward the haloid salts in presence 

 of sulphuric acid of definite strength. We showed in brief, 

 that when amounts of potassium iodide ranging from 0*005 

 grm. to 0*5 grm. were dissolved in 100 cm 3 of water contain- 

 ing 2 grm. dihydrogen potassium arseniate and 20 cm 3 of a 

 mixture of sulphuric acid with water in equal volumes, the en- 

 tire amount of iodine was expelled on boiling down the solu- 



* This Journal, vol. xxxix, p. 188. 



