The highest temperature is obtained when the ratio of fuel to oxidizer (potassium perchlorate, ammonium perchlorate or potassium nitrate) is about 1/5. For this ratio, the maximum temperatures obtained are as follows:

In the case of low temperature class sodium D (Na-D) lines (5890 and 5896 Å, caused by impurity contained mainly in the oxidizers), continuous spectra (caused by carbon particles and potassium atoms) and K lines (5802, 5783, 5832, 5813; 5340, 5324, 5360, 5343; 5090, 5084, 5113, 5080; 4044, 4058 Å) are observed. In the case of high temperature class Na-D lines are also observed, and in addition to the above, MgO bands and continuous spectra (the latter are caused by solid metal oxide particles and K atoms) are found.

The main spectra of disturbance are Na-D lines and continuous spectra. Purification of ingredients is very important to remove Na-D lines and to obtain fine colored flames. In the case of high temperature class, the addition of ingredients of chlorine compound such as polyvinyl chloride, ammonium chloride, etc. to a composition is effective to decrease intensity of the continuous spectra, and it is supposed that the metal oxide of the solid phase is converted into the metal chloride of the vapor phase in the presence of chlorine or hydrochloric acid in the flame, but this should be ascertained by further experiments of higher accuracy. The addition of shellac is also effective to weaken the intensity of the continuous spectra, decreasing the temperature of the flame.

The permeability coefficients and black body temperature of flames of basic compositions are measured for reference.

(2) According to the results of (1), various samples of red, yellow, green and blue of several composition series are prepared. Their flame colors are examined by the naked eye and good colors are selected. According to these, effective color zones are written as circular lines in trigonometrical graphs.