- 



In Table 1, the amount of concentrated acid used in each treatment and the 

 approximate proportion of acid to starfish (column 3) has been calculated. Samples 

 of each batch were ground and analyzed for nitrogen and carbonate. On the biisis 

 of previous analytical data, it was estimated that the initial nitrogen content 

 was 4.90 percent and the ealcium con- 

 tent was 58 percent of the dry matter » 



These data (Table 1 and Figure 1) 

 indicate that the nitrogen content 

 is not greatly affected by the acid 

 treatment, but that the variation 

 which does occur is opposite to that 

 which would be expected. In general, 

 the lots which received the most acid 

 have the lower nitrogen content . Since 

 the condition of the samples did not 

 indicate that this result could have 

 been due to post-treatment decompo- 

 sition of protein, which should have 

 led to the exactly opposite effect, 

 it would appear that the nitrogen was 

 lost at the time of acid treatment, 

 presumably by hydrolysis of part of 

 the starfish protein to a soluble form 

 which was then leached out. 



The calcium carbonate remaining figure i - relationship of the calcium carbonate 

 is a measure of the extent of the ac- AN0 nitrogen contents of raw starfish (dry basis) 



xo a moaoujBui iu» ""'"' <■ "«'J »»- T0 THE AMOUNT OF CONCENTRATED SULFURIC ACID USED 



tion of acid with this component. A IH their treatnent for fertilizer. 

 greater proportion of acid reacted 



with carbonate at the lowest levels of acid used. As the amount of acid was in- 

 creased, the amount of unchanged calcium carbonate decreased as shown in Figure 

 1. The proportion of acid which reacted decreased also, until when the most acid 

 was used only about one-half of the acid was found to have reacted with carbonate. 



A portion of the excess acid must have reacted with or have been absorbed by the 

 protein, as some preservative effect was obtained. However, most of the acid which 

 did not form sulfate was most probably lost on the ground as run off. Even when 

 the acid used amounted to nearly one-fifth of the weight of the wet starfish, it 

 did not neutralize much more than 60 percent of the calcium. The excess alkaline 

 ash must soon have restored the mixture to a nearly neutral reaction; whereas, with 

 the menhaden type of fish meal, small amounts of acid are sufficient to maintain 

 an acid reaction. 



CONCLUSIONS 



Raw starfish, on the basis of chemical analysis, is rated as a fair source of 

 nitrogen for fertilizer and as a poor or unimportant source of phosphorus and po- 

 tassium. The calcium carbonate it contains would be beneficial when used on acid 

 or heavy clay soils. 



Treatment with sulfuric acid is not a very effective means of preventing de- 

 composition of raw starfish to facilitate its use as fertilizer because of the 

 large quantities of acid required. To delay decomposition, concentrated acid 

 amounting to 15 percent of the weight of the raw starfish is required. 



