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112

In order to estimate the tenacity of the 
soap suds, the circumference of the larger part of the bubble should not be estimated, but that of the circle around which the observed colour
is exhibited. Experiments should be made on
the relative tenacity of soap suds and pure water by means of the balance and a disc of wood on the surface of the liquid. 

The bubble may be allowed to break of itself by the gradual running down of the water from its top towards the underside, and the colour which it exhibits at any one circle may then be noted. In this way the pressure of the air within may be avoided.
[[note in margin on left side]] This cannot be [[\note in margin on left side]]
 That the weight suspended is supported by the circle of the bubble which is under consideration, will be evident from the consideration that a ribbon attached to the top and passed along the circumference of the globe would be equally tended through its whole length, if it were to be passed over pullies, but the air within which supports the ribands is without friction, and therefore each riband or rather [[?]] supports its share of the weight.
It may be said that the weight suspended
will apparently be increased by the weight
of the upper part of the bubble, or by that of the part above the coloured ring. But the evaporization will lessen the weight as much as this quantity will increase it. 
Make experiments on pure water, and also distilled water with a solution of soap.
I find that drops of water vary very much in sise with the form and size of the vessel from which they are let fall
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[[leftheader]]April 19th, 1844[[/leftheader]]
[[rightheader]]113[[/rightheader]]

Made to day a new series of experiments on soap bubbles. The soap used was the common rosin soap dissolved in rain water. The method of determining the tenacity of the bubble was as follows.
[[IMAGE]] A bubble was blown on a ring of about half an inch in diameter by means of the bowl of a pipe, and the lower part brought into contact with the plate of [[/IMAGE]] the balance, to which it adhered, and on being drawn upwards it elongated into the form of a cylinder and drew up the scale pan. This cylinder became smaller at about e , and finally broke off at this point. The neck becoming less and less in diameter, and the thickness less and less as was evident from the exhibition of colours. In this way I succeeded in raising about four grains to the inch of the surface of the film, and allowing this just before it broke to be according to Newton's table of thin plates, (See Optics Brewsters, page 103) to be the one millionth of an inch thick, we will have a tenacity of 4 millions of grains in a session of such fillms an inch square in area. This will be nearly equal to 500[[strikethrough]0[[/strikethrough]] lbs avoir dupois per square inch.
The above experiment gives us the tenacity of soap water to find the relative attraction of soap water and pure water. For this purpose we may use the method of the disc, drawn from the water or the method of the capillary tube, both will give the relative attraction. By both these methods, I find the attraction of pure water for itself greater than that of soap water.  
I find the ratio of the tenacity of the two waters is as 125:100.  The attraction gave about 40 grains to the square inch, the glass disc was 2 inches in diameter.
The tendency to seperate into two bubbles interfered {written up right side of page]] with the result.

Transcription Notes:
avoir dupois is a weight unit