croup, 34; whooping-cough, 22; measles, 17; influenza, 8; scarlet fever, 7; and all others, 18.

The following table gives the number of deaths from certain principal causes for July, as well as the proportions from each cause per 1,000 totals deaths for both July and June:

Geographic Divisions.-The table below shows the number of deaths from main classes of diseases for the several geographic divisions of the State in July:

PLAGUE.

Five cases of plague occurred in San Francisco during the first half of August, all of them near the docks. One case was a sailor from the steamer "Samoa," plying between California points. He had spent but thirty minutes on shore for a month, and the vessel being ratinfested, he no doubt received his infection from them. The steamer was ordered into quarantine and thoroughly disinfected and crew retained.

The other cases lived near the docks in cheap, temporary shacks, built after the fire. All infection in them has been destroyed. All coastwise and deep-water ships will be sulphured for the destruction of vermin, a close watch kept on all deaths that can, in any way, be regarded as suspicious, a destruction of possibly infected goods where cases occur, a thorough disinfection of infected places, and rats destroyed. Although a few more cases may occur, the active steps being taken will, we feel sure, soon stamp out the infection.

PROFESSOR JAFFA.

The appointment of Prof. M. E. Jaffa as Director of the Pure Food Laboratory of the State has been received with unusual approval. It at once gives the department a standing that would take months of hard work to attain with a man less favorably known. The regard which the General Government feels for Professor Jaffa is shown by the Secretary of Agriculture personally asking him to take part in the work which they are now doing to solve the question of sulphuring fruit. In this work Professor Jaffa will be able to aid not only the State, but the Nation, with his thorough knowledge of the subject, and his great ability at arriving at safe conclusions from investigations.

TESTS OF DR. LEININGER'S SOLIDIFIED FORMALDEHYDE.
BY MARGARET HENDERSON,

Assistant in the State Hygienic Laboratory.

Dr. George Leininger's Solidified Formaldehyde, according to the pamphlet. which sets forth its merits,* is "a pure, concentrated, solidified product which is possessed, when volatilized by the simplest process possible that of superheating in an open receptacle with the flame of an alcoholic lamp-of the agent's full potencies and properties that render it invaluable for the double purpose of sanitary and thereapeutic adaptation." The series of tests which we applied to it were designed only to test its efficiency as a room disinfectant, under the ordinary conditions of house disinfection.

The solidified formaldehyde is an unctuous paste of about the consistency of mutton tallow, and has a strong smell of formaldehyde. The directions for its use given in the pamphlet are as follows: "Close all doors and windows, and carefully stop all avenues through which the gas may find escape-grates, stovepipe holes, registers, etc., should be tightly sealed; remove vessels containing any quantity of water, to avoid unnecessary absorption of the gas; suspend blankets and other

*Solidified Formaldehyde: Its Sanitary and Therapeutic Employment, with Reports of Bacteriologic tests and therapeutic results.

*

*

bedding over chairs to give the formaldehyde gas as free access thereto as possible. When the contents of the room are few and of such character as to present no obstacles to the access of the gas to the germs, less than one half of one ounce will suffice to formalize 1,000 cubic feet of space."

The test disinfecting was done according to these suggestions under a variety of conditions approximating as nearly as possible the varied conditions met in house disinfection. The test objects were bits of filter paper, about 1 mm. square, sterilized in petri dishes, then inoculated with twenty-four hour bouillon cultures of the organisms used, dried for two hours in the incubator, exposed to the gas in the opened petri dishes, and then at the end of the exposure planted in bouillon. The bouillon was always incubated for forty-eight hours at 37° C.

I started out by using just twice the amount of formaldehyde recommended for ordinary purposes. The results of the experiments with this amount of formaldehyde, one ounce per 1,000 cubic feet, are shown in tables 1, 2, 3 and 4 in detail, and summed in table 5.

Time for volatilizations of formaldehyde, 28 minutes.

Organisms: B. typhosis; Ps. pyocyanea; M. pyogenes aureus; B. anthracis; B. subtilis.

Space, 979 cubic feet.

Formaldehyde, 30.3 gr. (1 ounce per 1,000 cubic feet.)

Water, 60.0 cc.

Time of volatilization, 20 minutes.

Exposure, 3 hours.

Organisms: B. subtilis; B. typhosis; B. coli; M. pyogenes aureus; Ps. pyocyanea. Temperature, 25.6° C.

Humidity (at beginning of exposure), 93%.

Formaldehyde, 32.3 gr. (1 ounce per 1,000 cubic feet.)

Water, 32 cc.

Time for volatilization, 25 minutes.

Organisms: B. subtilis; B. typhosis; B. coli; M. pyogenes aureus; Ps. pyocyanea;

B. prodigiosus.

Exposure, 24 hours.

Temperature, 16° C.

Humidity (at beginning), 78%.

In the test shown in Table I, the room was an air-tight one arranged in the laboratory; in the rest, the rooms were of the ordinary dwellinghouse sort, with plastered walls, and ordinarily tight doors and windows. All openings were closed, but the windows and doors were not sealed.

The greatest difficulty arose in knowing when to open the room to take out the generator. In one case it took twenty minutes, and in one case one hour, to volatilize the formaldehyde, instead of the ten

minutes to the ounce given as the usual time in the pamphlet. This slowness in volatilization led to considerable loss in formaldehyde, because the door had to be opened several times during the process to see whether it was yet completed. The danger of fire led to great unwillingness to leave it longer than was entirely necessary.

The results of these four experiments would tend to show that Solidified Formaldehyde is only an indifferent surface disinfectant, sterilizing but 67 per cent of the test objects when used in the proportion of 1 ounce to 1,000 cubic feet, and can not be depended on at all for penetration.

The last experiment was tried with a larger amount of formaldehyde, 2 ounces per 1,000 cubic feet, or four times that recommended by the pamphlet (page 3) for surface disinfection, and the maximum recommended "when unusual permeating potency is demanded, sufficient to kill bacteria protected by several folds of blanket." Table VI gives the results of this experiment:

Space, 778 cubic feet.

TABLE VI.

(In a room of dwelling house.)

Formaldehyde, 48.28 gr. (2 ounces per 1,000 cubic feet.)

Water, 48 cc.

All of the thirty-seven test objects exposed on the surface were sterilized, but the penetration was scarcely better than with the other set of experiments, even though the exposure was much longer and the formaldehyde was volatilized quickly.

I would conclude then that, so far as our experiments go, Dr. Leininger's Solidified Formaldehyde seems to be an efficient surface disinfectant when used in the proportion of at least two ounces per 1,000 cubic feet, but can not, at that proportion, be depended on for any penetration. The fire risk in using it is not to be disregarded.

The probability that much of the disinfecting done is not at all effective is clearly shown by the above report, The solid formaldehyde generators, of which the Leininger is a type, are quite generally used throughout the State, and a belief that they were not effective, especially with the amount of material used, led to the series of tests which is reported Health officers will note the fact that the penetrating power is small, and if they continue to use this method, instead of the permanganate of potash method, much larger quantities must be used.